Germany [Images] will be without captain Michael Ballack [Images] for Friday's World Cup opening match against Costa Rica in Munich because of a calf injury.

"It seems Michael will not be on the pitch for the Costa Rica game," coach Juergen Klinsmann said at a news conference on Thursday.

"We'll leave him on the sidelines for this game and have him fit for the next one. It's annoying but not the end of the world. There's always someone who can jump in."

Ballack, who also missed the final match of the last World Cup because of suspension, suffered a slight strain to his right calf during Germany's 3-0 win over Colombia in a warm-up match on June 2.

The 29-year-old midfielder did not believe it to be serious at the time and alarm bells only started ringing when he was unable to train with the squad on Monday.

He did return to full training on Wednesday but had to drop out after just 30 minutes.

"The important thing now is to look ahead," Klinsmann said. "We want a fully fit Michael Ballack, not a 50 percent player. Fingers crossed he'll be back training soon.

"The doctors are working round the clock."

LIGHT TRAINING

Klinsmann said Ballack, who joins Chelsea from Bayern Munich next season, would fly with the team to Munich and could take part in a light training session at the stadium later on Thursday.

His target will be to get fit for Germany's second Group A game against Poland in Dortmund on June 14. The Germans wrap up the opening phase with a match against Ecuador in Berlin on June 20.

Klinsmann said Ballack would be replaced in the opening game either by Tim Borowski or the more defensive Sebastian Kehl.

Borowski looks the more likely candidate. He was outstanding in a 7-0 win over Luxembourg on May 27 -- the last time Germany lined up without Ballack.

Borowski is fit, in form and has a great understanding with centre-forward Miroslav Klose [Images], his team mate at Werder Bremen.

The absence of Ballack will nevertheless be a huge blow.

Ballack has scored 31 goals in 65 matches for Germany. He was outstanding in Germany's run to the final of the World Cup in 2002, which they lost 2-0 against Brazil [Images] with Ballack forced to watch from the sidelines because of suspension.