Kevin De Bruyne will miss the next 10 weeks after suffering medial ligament damage in Manchester City's 3-1 Capital One Cup victory over Everton, the player confirmed on Thursday night.
De Bruyne came off the bench to level the tie on aggregate before setting up Sergio Aguero to score the winning goal, which saw City book their place in the final against Liverpool on Feb. 28.
However, the Belgium international was stretchered off in the final moments of the game and he revealed on Twitter he will be out until April:
Just got back from the specialist. I'll be out for around 10 weeks.
- Kevin De Bruyne (@DeBruyneKev) January 28, 2016
He added: "I'll work hard on my recovery and hope to be back on the pitch asap. Thank you all for the supportive messages!"
Earlier on Thursday, his agent Patrick de Koster told Sky Sports that the player would be out for at least six weeks.
"I spoke with him half an hour ago and he is a little bit sad because he has got a tear in his ankle and also the ligament in his knee are touched," De Koster said.
"I think for sure he will need six weeks of rehabilitation.
"He is still going to do some more medicals today and at the end of the day I think, at least tomorrow morning, we will have the time he needs to be 100 percent again."
De Bruyne is set to miss the Capital One Cup final against Liverpool at the end of February, both legs of the Champions League round of 16 clash with Dynamo Kiev and key Premier League home games against Manchester United and Tottenham Hotspur.
"Kevin is sad," De Koster said. "His dream is to always be playing football. He will miss games like the League Cup final and in the Champions League, which are important.
"But he knows [City] are a good team, that the other players will do what they have to do, and maybe win the game for him, and also that [injuries] is what happens in football.
"He is sad, of course, but he told me, 'This [happens] in a match, [it's something] which can arrive in football, and the only thing I can do is to work hard and to come back.'"
The 24-year-old joined City from Wolfsburg in August for a reported £54 million and has quickly established himself as a leading star in Pellegrini's squad.
He made a huge impact when he came on as a substitute in the 67th minute as the two-legged tie swung in City's favour.
Pellegrini added: "I always said Kevin is a very important player in the whole season. He didn't start because we have to play nine games in 27 days.
"I think it is important to have a very good rotation of the squad. The minutes he played he did very well."
Everton goalkeeper Joel Robles apologised to De Bruyne after the game for attempting to pick the player up as he lay down in pain. The Toffees, though, remain incensed about the manner of their defeat, with Everton captain Phil Jagielka labelling referee Martin Atkinson "a little bit arrogant" in his attitude.