(Reuters) -Germany midfielder Bastian Schweinsteiger has not been a happy camper at the World Cup in Brazil.

The brooding 29-year-old jogged silently with goalkeeper Manuel Neuer at Germany's training session on Friday without a smile or a word in the direction of dozens of journalists, fuelling speculation he is perturbed by his role as a reserve.

A jovial and loquacious player at the last two World Cups in Germany and South Africa - when he played all 12 matches on teams who reached both semi-finals - Schweinsteiger has ignored the media in Brazil and will not speak to German TV.

"He's the kind of player who would rather do his talking on the pitch," said Germany spokesman Jens Grittner when asked about German media reports that Schweinsteiger was unhappy about only starting one of the three group matches.

Schweinsteiger, who has 104 international caps, sat on the bench for all of Germany's 4-0 win over Portugal and played only the final 20 minutes of the 2-2 draw against Ghana.

"He delivered his answer on the pitch yesterday," Grittner added, referring to Schweinsteiger's widely praised performance on Thursday in the 1-0 win over the United States that clinched first place in Group G.

"The coach's opinion of him was quite positive."

Coach Joachim Loew told German TV: "Bastian Schweinsteiger did a very, very good job."

Yet Schweinsteiger, replaced in the 76th minute, still ignored reporters waiting to talk to him in the mixed zone on the way to the team bus after the match in Recife.

Hours later Schweinsteiger did wave briefly to fans who shouted his name as they stood behind police barriers while he got off the bus to get on the ferry for the crossing to the Germany team quarters on an isolated beach.

In training on Friday, Schweinsteiger did not take part in the regeneration workout with the other starters on exercise machines in the shade under a shed and jogged with his Bayern Munich team mate Neuer.

It is likely that Loew will start Real Madrid's Sami Khedira, who needed a rest on Thursday, instead of Schweinsteiger.

"The truth behind Schweinsteiger's silence," read a headline on Friday in Die Welt newspaper.

"The suspicion is that he's sulking because he doesn't feel he's being treated appropriately. There could be some truth to that. Playing so little is an unusual situation for a star like him."