Switzerland captain Alexander Frei has been ruled out of action for six weeks as a result of the ligament tear that has ended his involvement in UEFA EURO 2008.

The Borussia Dortmund striker will however remain with the squad as they battle for survival in Group A following Saturday's 1-0 defeat by the Czech Republic in the tournament's opening match.

"It's a tough blow to lose your captain and leading scorer," acknowledged Swiss coach Kobi Kuhn. "But we can't afford to look back. The match against Turkey on Wednesday is now a final for us and we absolutely have to win it."

Kuhn added: "He has told us he wants to stay with the squad and if he had not said that himself I would have begged him to stay. Alex is a leader and he remains a leader."

Frei will however be badly missed on the pitch. With an impressive record of 35 goals in 60 internationals, he is the leading scorer in Switzerland's history and his loss has been compounded by concerns over the form and fitness of his regular strike partner, Marco Streller. Streller, 26, was left nursing a groin strain after Saturday's match which is to be assessed by the team's medical staff on Monday.

Frei suffered the injury to his left knee while contesting a 50-50 ball with Czech defender Zdenek Grygera just before half-time in the match. "He knew at once that his tournament was over," team doctor Cuno Wetzel revealed. "It was a partial tear of one of the interior ligaments and he will need at least six weeks to recover."