Michael Ballack remains confident that he will be fit enough to play in Germany's opening Group A clash against Costa Rica on Friday.

There had been fears that the 29-year-old Chelsea star would be forced out of the game with the calf injury he sustained in the 3-0 warm-up win over Colombia last Friday.

However, he insists: "It is not that bad, just a little bit sore.

"I think I will be able to play. I could not practice on Monday but I hope it will get better day by day so that I can play on Friday."

Assistant coach Joachim Low added: "His injury dented the atmosphere a little.

"We hope he will be back in practice soon. He knows about his importance for the team and we are all optimistic that he will be able to play."