West Ham winger Luis Boa Morte could be out until 2010 after suffering anterior cruciate ligament damage in his right knee at the Asia Trophy in China.
The 31-year-old was injured during Wednesday's 1-0 defeat by Tottenham.
Boa Morte hurt his right knee after catching his studs in the turf at the Beijing Workers Stadium following a tackle with Spurs' Benoit Assou-Ekotto.
West Ham boss Gianfranco Zola said: "It is a big blow. He's an important player for us both on and off the pitch."
Boa Morte was taken to hospital with his knee in a brace and further tests will determine whether he needs surgery.
The injury happened only 10 minutes into a goalless first half in a game that was settled by Jermain Defoe's solitary strike.
Tottenham striker Roman Pavlyuchenko came closest to breaking the deadlock in the opening 45 minutes but his curling effort came back off the post.
Spurs dominated for long periods and deservedly took the lead after 75 minutes when Defoe's shot squeezed past West Ham keeper Rob Green and trickled over the line.
Spurs will play Hull, who beat Beijing Guoan 5-4 on penalties, in Friday's final.
Geovanni opened the scoring for the Tigers, but his ninth-minute effort was cancelled out by Beijing's Mobido William just after the break.
The game ended 1-1 and Hull kept their composure to win the penalty shootout.