Marcel Keizer, the manager of Sporting Lisbon, has conceded Bruno Fernandes could leave the Portuguese club this summer.
Manchester United are interested in signing the 24-year-old as Ole Gunnar Solskjaer eyes reinforcements in midfield following the departures of Ander Herrera and Marouane Fellaini.
Keizer hopes Sporting can keep hold of Fernandes but admitted they won't be able to retain all of their best players.
"For me they can close the [transfer] window, yes," Keizer said. "It would be enough for me. At all times, before starting, one expects exits and entrances. We have to wait.
"We want to keep the best, but we're in the market. Soon we have to wait. We are not in the position where we can keep everyone. Let's hope it stays that way."
Asked whether Sporting will be affected next season if Fernandes leaves, Keizer responded: "It depends, of course, on who can enter later if Bruno leaves. Quality players like that we can't replace."
Fernandes himself spoke to reporters on Monday night and said he was unsure whether Sporting's upcoming friendly with Liverpool in New York would be his last game for the club.
"The president decides that, not me," Fernandes told A Bola. "I don't care about the market, I've talked about this many times.
"The only thing I can do now is that I need to catch the plane so I don't miss it. Will this be the last match for Sporting? I don't know, it's the coach who decides.
"I said I'd like to play in England, but I don't care about it right now. If it could be this season? It could be when the club decides, I'm not in charge."
