Germany captain Michael Ballack has emerged as an injury doubt for Sunday's Euro 2008 Final against Spain.

The Chelsea midfielder sat out training on Friday with a calf injury and could miss the showpiece at Vienna's Ernst Happel Stadion.

The absence of the 31-year-old skipper would be a major blow to coach Joachim Low after his impressive form during Germany's drive to the final.

Ballack has scored twice in the tournament - against Austria in the group stage and Portugal in the quarter-finals - but is no stranger to sitting out major international occasions after missing the 2002 World Cup final against Brazil due to suspension.

Speaking after Germany's 3-2 semi-final success over Turkey on Wednesday, Ballack had revealed that he and several team-mates were running on empty after a long club season.

He said: "Our legs were a bit heavier, the team are tired, but we're happy, we're in the final and that's what counts.

"We're going to take a break for a few days and build up our strength because we'll need it."