West Ham manager Gianfranco Zola's fears were realised on Wednesday afternoon when scans confirmed Luis Boa Morte has suffered a serious injury to his right knee.
The Portuguese winger was hurt when he caught his studs in the turf following a challenge with Tottenham's Benoit Assou-Ekotto in the Hammers' Barclays Asia Trophy clash in China.
Boa Morte was taken to a city centre hospital where tests showed he had damaged his anterior cruciate ligament, which could rule him out for several months.
A statement on West Ham's website said: "West Ham United can confirm that Luis Boa Morte could be out until 2010 after suffering anterior cruciate ligament damage in his right knee.
"Boa Morte will undergo further tests to determine whether or not he will require surgery when the swelling on his injured knee goes down."
Following the match, which Spurs won 1-0, Zola had been optimistic the 31-year-old, who featured in more than 30 games last season, would not be facing a long spell on the sidelines.
"It is a big blow for me," said Italian Zola. "He is an important player both on the pitch and off the pitch.
"Hopefully it is not too bad as he is a vital player for us."
Boa Morte was taken off in the 14th minute and West Ham never really got into the game after that as Jermain Defoe's late strike was enough to secure victory for Harry Redknapp's side at Beijing's Workers Stadium.
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