Belgium striker Christian Benteke was ruled out of the World Cup after rupturing his Achilles tendon in training with English Premier League team Aston Villa on Thursday.
Benteke will undergo surgery and "will be out for a minimum of six months," Villa said in a statement.
It is a major blow for Belgium's chances in Brazil, with the 23-year Benteke having been battling with Romelu Lukaku to be the team's main striker.
"Wishing you all the strength you need," Belgium captain Vincent Kompany said on Twitter, "and I hope you will recover quickly! We're all with you together."
Belgium, which has emerged as one of the top teams in Europe in recent years, is well stocked in most departments in its squad but has a dearth of proven, all-out strikers.
The powerful Benteke is Villa's top scorer in this campaign with 11 goals, although he has struggled to recapture the form that made him one of the Premier League's most lethal strikers last season.
Fitness permitting, Lukaku and Benteke would have been fierce rivals to start in Belgium's opening Group H game against Algeria on June 17, especially after Lukaku's superb season with Everton on loan from Chelsea. Russia and South Korea are the other teams in the group.
"It's a terrible blow both for Christian and for the club," Villa manager Paul Lambert said. "He will miss the rest of the season, obviously, and also the World Cup.
"But he'll work hard because that's what he does and he'll come back for us stronger than ever next season."
Lukaku has scored six goals in 18 games for Belgium.