When Thibaut Courtois swapped Chelsea for Real Madrid, it was a decision that was met by Blues fans with anger and criticism.
Perhaps the Belgium international was a bit of a 'snake' in the way he went about securing his move to Madrid, but a large part of fans' anger didn't stem from his actions to complete the move - but rather the fact that they were fully aware that they were losing a world class goalkeeper and one of the best in the business.
For around £35m as well, it appeared as though Real Madrid had made an excellent signing. But as it turned out, Courtois made a very slow start to life at his new home, struggling to make the comfortable saves any goalkeeper of his calibre would have been expected to make.
Indeed, it was tough for him as Keylor Navas was a fan favourite at Los Blancos, and equally, a key member of the Real squad. The players trusted him, supported him and backed him - which, of course, only made things more challenging for new arrival Courtois.
As first impressions go, Courtois' didn't make a great one, so much so that talk even began to grow that Los Blancos were considering the possibility of selling him after just one season. The same problems persisted early in the 2019/20 campaign, as well.
But fast forward one year and Courtois is now once again regarded as one of the world's very best. And while Karim Benzema and Sergio Ramos as well as boss Zinedine Zidane will receive the main plaudits for recently securing their 34th La Liga title, Courtois has been equally vital to this Real side.
He's looked unbeatable at times, producing world class saves while also getting his side playing on the front foot with his range of passing. The 28-year-old's importance to his side's title triumph cannot be understated.
Take his performance in the most recent Clasico, when Los Blancos won 2-0. The former Chelsea man produced three stunning saves to deny Arthur Melo, Lionel Messi and Martin Braithwaite in one-on-one situations, before the hosts opened the scoring through Vinicius Junior after 70 minutes.
In doing so, Courtois became the first Real goalkeeper to keep clean sheets in both Clasico league fixtures since the 1974/75 campaign.
In total this season, Courtois has managed 18 clean sheets in the league, while Real have conceded just 23 goals so far. Furthermore, the Belgian has managed a save percentage of 52.9%, while Jan Oblak and Marc-Andre ter Stegen - both of whom are regarded as two of the world's finest shot-stoppers - have managed 45.9% and 38.9% respectively.
Kepa, the man tasked with replacing Courtois at Chelsea, has a save percentage of just 25% in the Premier League in 2019/20.
Despite his tough start, Real's number one has remained focused and has worked tirelessly to ensure he would succeed at the Bernabeu. And this is exactly what he has done.
But more broadly, his success at Real shouldn't come as a surprise because the club's recent title win means Courtois has now won the league at every club he has played for. This isn't coincidental, nor is it fortunate for him - rather it is because of his skills and ability to constantly learn and want to improve.
During his early days at Genk, a club he joined aged seven, he made his debut aged just 16. And in the 2010/11 season, he went on to pick up the Goalkeeper of the Year award as well as Genk's Player of the Year as he helped guide them to league glory.
A move to Chelsea soon followed for the young talent, but he was quickly sent on loan to Atletico Madrid - where he would shine. Indeed, he was named Man of the Match as he put in a simply outrageous display to help his loan club overcome rivals Real 2-1 for the first time in 14 years in 2013. Oh, and it was in the Copa del Rey final as well.
He went on to play a key role in Atletico's 2013/14 La Liga success, with his performances helping Atletico win the league as well as reach the Champions League final.
This was a goalkeeper going from strength to strength, and Chelsea simply couldn't ignore him any longer. Indeed, he was brought back to Stamford Bridge for the 2014/15 season, and success continued to follow Courtois as he helped the west Londoners win the League Cup and the Premier League in his first season back.
The 2015/16 campaign was tough for the player as he struggled with injuries, while he also saw red twice that season. But as has been made evident throughout his career to date, Courtois is a player that is always looking to learn and improve, which is exactly what he did - conceding just 28 league goals the following season to help the Blues become Premier League champions again.
Courtois has been criticised by many, but his record speaks for itself. His performances this season for Real Madrid have gone somewhat unnoticed, but Zidane will be fully aware of the key contributions he has continued to make and just how vital he has been to their title win.
Their league triumph was built on defensive solidity, and Courtois' leadership, shot-stopping and distribution has been key to this. Make no mistake about it, the goalkeeper is one of the very best in the business.