Paris Saint-Germain are said to want one of Vinicius Junior, Raphael Varane, Thibaut Courtois or Keylor Navas if they are to sell winger Neymar to Real Madrid.
Neymar is widely expected to be on his way out of PSG this summer, with Real and Barcelona leading the race for his signature. However, given the magnitude of the deal, both clubs are looking at player-plus-cash offers, rather than trying to meet PSG's asking price.
According to Telefoot, there are a number of options for Real. Los Blancos are believed to have already failed with an offer which would see Gareth Bale head to Paris, with the Ligue 1 side looking to receive one of the four aforementioned players in return.
Real are adamant that Vinicius and Varane are off the table, so it looks like it could come down to one of their goalkeepers. Courtois is believed to have rejected the move, but Navas is thought to be open to leaving for PSG.
However, should Navas be included in the deal, it is likely that Real would have to offer PSG more money, given he is the least valuable out of the group.
The 32-year-old looks to be firmly behind Courtois in the pecking order at the Santiago Bernabeu, and it is thought that Navas would be eager to leave Real in search of regular first-team football.
Both Manchester United and Porto were credited with an interest in Navas earlier in the summer, whilst PSG were also believed to be keen after missing out on David de Gea, and Real's interest in Neymar has seen PSG reignite their pursuit of the Costa Rica international.
Since joining from Levante in 2014, Navas has made 162 appearances for Los Blancos, the vast majority of which came as a first-choice goalkeeper. However, he was restricted to just ten La Liga appearances last season, usually only playing if Courtois was unavailable.
As a result, Real may be open to losing Navas in a swap deal for Neymar, but it will likely come down to how much PSG will demand in addition.
The club aren't blessed with infinite money and, after signing the likes of Eden Hazard, Luka Jovic and Ferland Mendy, coming anywhere close to PSG's €222m asking price will be easier said than done.