Despite the Derby della Madonnina being one of the most passionate and storied in football, the Italian loyalty charts are a bit strange.
Players regularly switch between the top sides in Serie A, and often to limited fan backlash.
Inter and AC Milan don't just share a stadium. In their history, a staggeringly high number of players have turned out for both Milan sides thus far. Scratching your head? Don't you worry - 90min has listed them for you.
38. Aldo Cevenini
A forward at the beginning of the 20th century, Aldo Cevenini switched allegiances more than once.
The Italian started with AC Milan and had a second spell with the Rossoneri, but played for Inter on three occasions.
37. Luigi Cevenini
Younger brother of Aldo, Luigi Cevenini followed the same path in switching between the two clubs.
He also played for others such as Juventus and captained the national side.
36. Giuseppe Meazza
Having built a career on being football's rock and roll star at the time, when Giuseppe Meazza wasn't banging in goals for Italy or partying with women and plenty of alcohol, he was in Milan.
He found success with Inter over a 13 year period before joining AC Milan in 1940. He only spent two seasons with the Rossoneri, though, and had a brief second stint with Inter later down the line.
35. Enrico Candiani
Midfielder Enrico Candiani similarly found most of his success with Inter, winning the Scudetto and the Coppa Italia with the club from 1938 to 1940.
After some time with Juventus and Pro Patria (now in Serie C), Candiani returned to Milan, but on the red side for one season only.
34. Lorenzo Buffon
Yes, he was a goalkeeper and yes, he is related to Gianluigi.
Lorenzo Buffon - cousin of Gianluigi's grandfather - was regarded as one of the best of his generation. He spent a decade with Milan after signing in 1949 and joined Inter in 1960, spending three years with the Nerazzurri.
33. Aldo Bet
The blueprint Italian defender, Aldo Bet only spent one year with Inter as a senior before moving on in 1968.
He found his stride in Milan after signing in 1974, becoming a regular in the side and eventually playing with Franco Baresi.
32. Fulvio Collovati
1982 World Cup winner Fulvio Collovati came through the youth ranks at Milan and debuted in 1976, sticking with the club amid their relegation to Serie B in 1979.
They were relegated again, though, and Collovati joined Inter instead in 1982 and forged a successful spell with the club over four years.
31. Aldo Serena
Italian forward Serena earned a move to Inter in 1978 having made a solid account for himself in Serie D, but was loaned out to just about everyone in his first spell.
He was loaned to AC Milan in 1982 (at the time in Serie B), and signed permanently for Juventus in 1985. Two successful years in Turin brought him back to Inter for a more fruitful second spell. But by 1991, he left again to join AC Milan for a second spell which tarnished his newfound Inter reputation somewhat.
30. Francesco Toldo
Goalkeeper Toldo came through the youth ranks at Milan but never racked up a senior appearance before leaving in 1993.
He signed for Inter in 2001 and stuck around for nine seasons, floating between first choice and backup roles.
29. Maurizio Ganz
Ganz had to earn his shot with Italy's top sides and spent much of his early career boosting his stock in Serie B with Monza, Parma and Brescia.
After impressing again with Atalanta, the striker signed for Inter in 1995 and enjoyed a prolific two seasons with the club, but couldn't clinch silverware. A move to AC Milan came in 1997, where Ganz helped the club to a Coppa Italia and a Scudetto in his first two seasons.
28. Christian Panucci
AC Milan snapped up Christian Panucci from Genoa in 1993, with his versatility earning him a way into Fabio Capello's side as a youngster.
After a brief stint with Real Madrid, Panucci signed for Inter in 1999 but failed to recapture his best form and left in 2001.
27. Cristian Brocchi
Tough tackling Cristian Brocchi rose through the youth ranks at AC Milan but couldn't find a way into the first team and left in 1998 after a series of loans.
He signed for Inter in 2000 but left a year later, slamming the club for the way they treated him and returning to the red side of Milan - a much more successful spell that lasted until 2008.
26. Roberto Baggio
Having been edged out of the door by Juventus, Roberto Baggio signed for Milan in 1995 and helped the club to a scudetto in his first season, but had fallen out of favour by his second year.
He signed for Inter following the 1998 World Cup and spent two years once again in Milan before moving on.
25. Taribo West
Nigerian Taribo West has a fascinating career path that has seen him play in the Italian and German top flights, but also seen him turn out for Al-Arabi and Plymouth Argyle.
Before that, the Championship Manager legend signed with Inter in 1997 and had a strong start before fading in influence. Mid season, he joined Milan in the 2000 winter transfer window, but was on loan in England by that November.
24. Andrea Pirlo
It's hard to actually pin where Pirlo's strongest stint was, considering he was a hit throughout his playing career in Italy.
Having broke through at Brescia, attacking midfielder Pirlo signed for Inter in 1998. He failed to break through between loans and runs in the side and signed for Milan in 2001, developing into one of the finest deep-lying playmakers around.
23. Francesco Coco
An exciting, young Italian left back breaking through in the 1990s, AC Milan thought they had the next Paolo Maldini on their hands in 1995.
That was quashed when he was sold to Inter in 2002, as a makeweight for Clarence Seedorf heading the other way.
22. Clarence Seedorf
It's a strange thought to process, but yes, Clarence Seedorf was once an Inter player, signing in 1999.
Seedorf impressed but failed to help them in their pursuit of silverware and left for AC Milan in 2002, where he thrived and picked up another two Champions Leagues for his collection.
21. Dario Simic
Having poached Pirlo in 2001, Milan were at it again the following year when they signed full back Dario Simic from Inter, with Umit Davala going the other way.
Carlo Ancelotti made immediate use of Simic as a right back instead of in the centre and stayed with the club until 2008.
20. Umit Davala
Davala followed former head coach Fatih Terim to Milan in 2001, but when he was sacked by November that year, it never looked good from then on in.
Following the swap deal, he never made an appearance for Inter and left permanently in 2004.
19. Patrick Vieira
Having impressed in France, midfielder Vieira earned a move to Milan in 1995, but only made two first team appearances before leaving a year later.
Following scandals surrounding Juventus and their Serie B relegation in the early 2000s, Inter snapped up a now top class Vieira on a cut-price deal in 2006.
18. Edgar Davids
The man with the goggles, Dutch midfielder Edgar Davids disappointed in his sole season with Milan in 1996/97.
He returned to Milan in 2004 with Inter, but was again gone after a year.
Midfielder Guly earned a move to AC Milan in 1998 after impressing in his native Argentina.
Injuries and inconsistencies began to get the better of him, however, and despite signing for Inter in 2001, he never made it stick again in European football.
16. Thomas Helveg
AC Milan made Thomas Helveg the most expensive Danish player in football in 1998 when they signed him from Udinese for £6m.
Helveg picked up a scudetto and the Champions League with the Rossoneri before leaving in 2003 and spending a season with Inter.
15. Christian Vieri
Having played for just about every Italian club to exist in the 1990s (and Atletico Madrid) Christian Vieri found a permanent home with Inter in 1999.
The forward shined at the 1998 World Cup and impressed when back in Italy with Lazio, earning a record move to the Nerazzurri and forging a respected career with the club. A cross-town move to Milan in 2005 resulted in a hellish half a season, with Vieri being crowned the worst player in Serie A for that calendar year. Ouch.
14. Drazen Brncic
Time spent in Milan was pretty forgettable for Croatian midfielder Drazen Brncic.
He barely got a look in with AC Milan from 2000/01 and never featured for Inter after signing for them at the end of that season.
Ronaldo signed for Inter in the same year as Taribo West. Incredible.
And despite a length injury absence that had his career in jeopardy, it was R9 who stuck it out with the Nerazzurri before moving onto Real Madrid in 2002. Ronaldo returned to Italy with AC Milan in 2007, but injuries and weight issues at the end of his career blighted what could've been another iconic stint.
12. Hernan Crespo
Recovered from injuries and raring to go, Hernan Crespo was signed by Inter in 2002 and tasked with replacing Ronaldo. No pressure.
He never quite found the form that propelled him to the top level in the 1990s and left the following summer for Chelsea. A season loan to AC Milan proved impactful as he scored a brace in the 2005 Champions League final. Crespo returned to Italy with Inter in 2006 and eventually made the loan permanent.
11. Antonio Cassano
Injuries and health issues blighted what looked to be a promising move to Milan for Cassano in 2010 and stopped him from becoming a regular in the XI.
He signed for Inter in 2012 in a player-plus-cash deal involving Giampaolo Pazzini, but failed to impress.
10. Giampaolo Pazzini
After just one season with Inter, Pazzini was used in a swap deal which saw him switch allegiances in 2012.
Pazzini carved out a solid three year stint with a Milan side that was unfortunately in decline.
9. Giuseppe Favalli
After a long stint with Lazio, Inter signed Giuseppe Favalli on a free in 2004 and he helped the club to two Coppa Italia trophies and a scudetto.
A short yet sweet stay ended when he signed for Milan in 2006, closing out his career as experienced backup for the Rossoneri.
Brazilian winger Mancini (yes, named after every Italian manager ever) found his stride in Rome as a tricky attacker and signed for Inter in 2008.
He failed to knuckle down, however, and was loaned to AC Milan in February 2010, but returned to Brazil just over a year later.
7. Zlatan Ibrahimovic
Inter snapped up Zlatan Ibrahimovic following Juventus' demise in 2006 and enjoyed the fruits of his labour until 2009 when he was sold to Barcelona.
His falling out with Pep Guardiola resulted in him joining AC Milan on loan in 2010/11, a deal that became permanent a season later. He returned to AC Milan in 2019.
6. Mario Balotelli
Before an explosive three year spell with Manchester City, Mario Balotelli had broken through at Inter and found success under Roberto Mancini from 2007 to 2010.
Balotelli returned to Milan in 2013 with the Rossoneri and was a hit with fans, replicating some of his best form that has barely been seen since.
5. Sulley Muntari
Following the beginning of the end for Portsmouth's spell at the top, Sulley Muntari joined Inter in 2008 and started strong before fizzling out.
He moved to Milan on loan in 2012 and made the deal permanent that summer, staying with the club until 2015.
4. Andrea Poli
A loan to Inter with an option to buy in 2011/12 seemed like Andrea Poli's big chance at the top. Inter decided not to purchase him, however, and he signed for Milan in 2013.
Poli spent four years with Milan in a dark period for the club, before leaving for Bologna.
3. Matias Silvestre
After just one season that had been interrupted by injury, Inter loaned midfielder Matias Silvestre to rivals Milan in 2013 and gave them the option to make the move permanent.
They declined, and Silvestre's career at the top fizzled out.
2. Leonardo Bonucci
Veteran defender Leonardo Bonucci was signed by Inter permanently in 2006, but never broke through and was sold off in bits to a myriad of Italian sides, in true Serie A fashion.
Having developed into one of Europe's best defenders in the 2010s with Juventus, Milan splashed the cash to sign Bonucci in 2017 to try and fix their issues, but it didn't work and he returned to Juve a season later.
1. Matteo Darmian
Manchester United legend Matteo Darmian actually rose through the ranks at Milan and made a handful of appearances before leaving for good in 2010.
He signed for Inter in 2020 and helped Antonio Conte's side to their first scudetto since 2010.