Frei left the pitch in tears after suffering the injury
Switzerland's influential captain Alexander Frei has been ruled out of the rest of Euro 2008 with the knee injury he suffered in the opening game.
Frei, 28, limped off in tears during the 1-0 defeat against the Czech Republic on Saturday.
Swiss team doctor Cuno Wetzel told a news conference on Sunday that Frei would be out for six weeks with a partially ruptured, left knee ligament.
"He was an important player. He was a goal-getter." said coach Koebi Kuhn.
"But he's out. We have to move forward."
Wetzel added: "Alex Frei knew immediately that he had been hurt badly."
The doctor said Frei would speak publicly on Monday, but now wanted "to have some time to himself".
The Borussia Dortmund forward missed much of the Bundesliga season because of injuries.
He has had a hip operation, two muscle tears and a calf injury in the last 13 months, but had battled back to full fitness in recent weeks.
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Frei suffered the injury in a challenge with Czech defender Zdenek Grygera shortly before half-time in the opening game of the tournament.
After the game he was sent to hospital for a scan and Kuhn said: "It is a shock, a disaster to lose our captain in the first game - I can only hope it is not too serious."
Frei became Switzerland's all-time top goalscorer last week when he scored his 35th goal in 59 internationals, and was seen as vital to the team's chances of getting out of a tough group that includes Portugal and Turkey.
"He's our best striker, we need him back in the team," defender Johan Djourou said after the match.
"We will take a lot of confidence from the way we played against the Czechs, especially in the first half, but if we lose Alex it will be very difficult to get back into the tournament."
Meanwhile, Kuhn said his team should be proud of their display, despite the defeat.
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