(Reuters) - Firm friends and former team mates at Real Madrid, Mesut Ozil and Sami Khedira make starkly contrasting contributions to a Germany side through to face Brazil in the World Cup semi-finals on Tuesday.

Ozil is perhaps Germany's most gifted ball player, blessed with superb vision and technique and a keen eye for goal, but he is also one of their most frustrating performers who has a habit of drifting away from the action.

Khedira, by contrast, who returned from a serious knee injury shortly before the finals in Brazil, is the classic midfield workhorse, whose tireless running and tackling seldom gets recognition but which is vital to the team's success.

Both could have a crucial role to play as Germany, eliminated at the last-four stage at consecutive tournaments, seek to secure their first appearance in a World Cup final since they lost to Brazil in 2002.

Ozil was one of Germany's brightest stars on their run to the last four at the World Cup in South Africa four years ago but has failed to consistently recreate that form at the latest edition of soccer's global showpiece.

It was a similar story at Real and has been at his new club Arsenal, with rare moments of brilliance punctuating a series of lifeless displays.

Khedira, 27, who has a Tunisian father and a German mother, has not been an automatic starter in Brazil but when coach Joachim Loew has deployed him he has turned in typically energetic displays.

His season at Real was wrecked by the knee injury sustained playing for Germany against Italy in November, but he returned in time to start May's Champions League final, when Real came from behind to see off city rivals Atletico Madrid.

He has 50 caps for his country and four goals.

Born of Turkish parents in the western German industrial city of Gelsenkirchen, Ozil had stints at Bundesliga sides Schalke 04 and Werder Bremen before his performances in South Africa captured the attention of big-spending Real.

Considered surplus to requirements under Jose Mourinho, he was sold to Arsenal where after a bright start he failed to live up to early expectations. The 25-year-old has made 50 appearances for Germany, scoring 18 goals.

BODY LANGUAGE

Former Germany captain and midfielder Lothar Matthaeus noted that Ozil has been playing out of position on the wings of midfield in Brazil, away from his preferred central role.

"Some players don't play in the same positions they do for their clubs," Matthaeus said on FIFA.com on Sunday.

"You can see that clearly with Mesut Ozil. He normally plays in the center of the park and now he's on the left.

"His body language isn't right and he doesn't seem as happy as usual. But he has to play there to get a game and he's giving his all."

Loew's assistant coach Hansi Flick rejected suggestions that Ozil had been a flop at the World Cup when asked about his role at a news conference on Sunday.

"We see that differently than you do," he told reporters.

"Mesut is playing a different position now than he used to and he's got a different assignment now.

"He's got very strong skills with the ball and on top of that he's improved during the course of the tournament.

"We're very satisfied with Mesut," Flick said. "He brings a lot of confidence with the ball into our game and is always ready for a pass."