Michael Ballack has added to Chelsea's injury woes after he was ruled out for two weeks after having surgery on his feet.

The 32-year-old Germany captain needed the operation to cure an infection after complaining of pain in his feet in the World Cup qualifying win over Wales, said a statement released by the German football federation (DFB).

Ballack, 32, had a neuroma - a thickening of nerve tissue most commonly found at the base of the third and fourth toes - removed from each foot.

The surgery, carried out with the agreement of Chelsea, was successful and the midfielder should be back in training in two weeks' time.

Luiz Felipe Scolari, the Chelsea manager, has been boosted by the return of John Terry for the match against Middlesbrough on Saturday but has been forced to draft in a host of youngsters for the trip.

Among them is Michael Mancienne, the England under-21 defender, and winger Scott Sinclair. Scolari is without regulars Petr Cech, Ashley Cole, Michael Ballack, Joe Cole, Didier Drogba, Michael Essien and Ricardo Carvalho, while Jose Bosingwa and Alex are doubtful for the game.

However, Scolari says he remains calm despite the injury crisis facing the club.

"I'm not angry," he said. "I'm happy because it's a test for me that I'm a good coach. I need to change it, to improve, I need to put other players in, I need to motivate other players. It's good for my job. It's not difficult. For me it's normal, I need to build every week, one different team.

"Many clubs have injuries from the national games because they are strong games. I worked yesterday with only 11 players. Today I worked with 17. It's better! Maybe Saturday I have 19.

"Against Roma in the Champions League next week, maybe I will have 20 or 21. This is the life for the coach. You need to understand we have different games and I need to understand that national teams want and need the players.

"The coach for a national teams doesn't want injuries for his players, he wants what we want - to win.

"It's not only one club that loses when national teams play. One time my club loses players, one time Liverpool, one time Man United. We need to accept this.