Porto defender Ricardo Pereira is among the names considered by Tottenham boss Mauricio Pochettino as a candidate to replace Kyle Walker, should the England full-back leave the north London club in the summer.
Sky Sports says Ricardo, who has spent the last two seasons on loan at Nice, has a £22m ($28m) release clause in his Porto contract and is within Spurs' price range for a new signing.
Paris Saint-Germain, Barcelona and Borussia Dortmund are also reportedly interested in the 23-year-old right-back.
Walker has a contract with Spurs until 2021 that is worth £70,000 per week. Sources told Sky that the England international was relaxed over his future and is not agitating for a move away from the north London club.
However, the 27-year-old is understood to be unhappy at not being selected for some matches towards the end of the season, with Spurs boss Mauricio Pochettino occasionally opting for Kieran Trippier at right-back.
Manchester Evening News reported that City would open talks with Spurs over Walker before the end of the week.
Walker told Sky Sports before England's games against Scotland and France that he was not thinking about his future and that he was enjoying his rivalry with Trippier.
"[It's not a distraction] – not at all. Coming away from club football gives you head space. I'm an England player now and we've got to concentrate on these games," he said on 7 June.
"[The rivalry] has pushed us both on as players, most definitely. We get the best out of each other. Even if Trips plays, or I play, we've said privately to each other than we'll will each other on.
"I don't ever say a bad word or wish bad on him because it's more about the team rather than individual performances."