Jose Mourinho does not know when Zlatan Ibrahimovic will return to action, but he has ruled him out of Manchester United's Champions League group games.
Ibrahimovic, 35, rejoined United on a one-season contract earlier this week, four months after undergoing career-saving knee ligament surgery.
But while the Swedish striker has been busy talking up his return on social media, Mourinho does not expect to be able to call upon him until next year.
"He will not be ready for the group phase of the Champion League. I don't think there is any chance of that," said Mourinho, whose side face Benfica, Basel and CSKA Moscow in Group A.
"I'm not thinking Zlatan to play any part of the group phase. Hopefully he can play in the knockout phase, but for that we need to finish top two.
"I don't want to think about it. I don't even ask, speak about it or with the medical team about it.
"He will be an extra man for us in the second part of the season. When I say second part, we say January after Christmas, when the transfer window re-opens, but I have no idea at all."
Ibrahimovic, who scored 28 goals in his first Old Trafford campaign, had been linked with a move to Major League Soccer and Mourinho said his desire to rejoin United showed his ambition was fully intact.
"It shows two things for me: it shows me the dimension of the player and the club," the United manager told reporters at the club's training centre in Carrington, west of Manchester on Friday.
"The player, it would be very easy for him to say goodbye. He had success at Man United, goodbye. He doesn't do that. He wants to follow his other dreams and play football at the highest level.
"And a club like Man United in my opinion has to show how big it is in details and this is a big detail of a player that gets injured with the Man United shirt, fighting for Man United.
"The club has to be there for him and I'm really happy with club and player."
Mourinho paid tribute to former United captain Wayne Rooney, who announced his retirement from the England team this week, and revealed he was in touch with the striker on the eve of his announcement.
"He told me the night before," said Mourinho. "I am nobody to agree, don't agree. I just listen to his reasons and I understand his reasons.
"He does it for Everton, for his family, so I have no complaints.
"I just realise like many other people when he retires, you realise how many matches he played, goals he scored, the football he represents in this country.
"Many congratulations for his career with the (Three) Lions."
Mourinho also reacted to Thursday's Champions League draw and said United's group would not be as easy as some pundits seem to think.
"My reaction is of somebody who played 120 matches in the Champions League and it's a completely different reaction than the reactions I listen to," he said.
"I think when you think about qualifying, it's better to have two top teams and two weak teams and let's see if we can finish second or first, but we are qualified.
"In this kind of group, everyone can win, lose, draw, and we are going to share the points in between teams. You are not going to see a 4-0 or 5-0, a team with 13, 14, 16 points, another with zero or one.
"So I think it's a dangerous group and if you go to the recent history of Man United, they lost to Basel (in 2011) and could not beat Benfica in two matches (in 2011).
"I think also against CSKA Moscow the last time was 0-0 or 1-0 or something (a 1-0 win in November 2015)."