Werder Bremen defender Per Mertesacker has undergone a successful operation on the knee injury he picked up at the club's training camp.

The Germany international is still likely to miss the start of the Bundesliga season however after he suffered the injury in training on Tuesday.

Bremen coach Thomas Schaaf revealed new signing Sebastian Prodl could take Mertesacker's place in the back four.

He told the club's official website: 'With him we have got ourselves an important man, who has enriched our team and made it stronger.

'He has demonstrated good commitment and a good attitude; he works hard and seems confident.'

Werder Bremen defender Per Mertesacker has suffered a serious knee injury that is set to rule him out of the beginning of the Bundesliga season.

Mertesacker damaged knee ligaments while training on Tuesday morning and left Werder's training facility on crutches.

'It didn't look good when it happened', Bremen captain Frank Baumann told the club's official website.

His fears were confirmed when doctors revealed that Mertesacker would undergo surgery on Wednesday, ruling him out of the first three to four weeks of the Bundesliga campaign.

Coach Joachim Loew has called up 19 players to Germany's squad for Wednesday's Euro 2008 qualifying match against Cyprus in Nicosia. The squad was announced on Thursday and back in the squad is Per Mertesacker. The centre-back playing for Werder Bremen has not been in the team since the World Cup this summer.

"Per was an important part of the team during the last two years. After his long lay-off due to injury, he got better and better at Werder Bremen and played on a high level in the Bundesliga and Champions League matches. After speaking with Bremen's coach Thomas Schaaf, I decided to call him up for the last match of the year", Loew said on Thursday.

Germany are second in the Euro 2008 qualifying Group D after beating Ireland, San Marino and Slovakia in their three games so far.