Franck Ribery has criticised Bayern Munich coach Pep Guardiola as he battles to be fit for Saturday's German Cup final showdown against Borussia Dortmund amidst the Bavarians' midfield injury concerns.

Spain midfielder Thiago Alcantara will definitely miss the clash at Berlin's Olympic Stadium having been ruled out of next month's World Cup after suffering a new knee injury on Monday while on the verge of making his comeback.

The German champions are also waiting on the fitness of defensive midfielder Bastian Schweinsteiger, who has strained knee ligaments, and winger Ribery, who is struggling with a back problem.

But Ribery said Guardiola's rotation sytem has not helped him with the Spaniard struggling to give his star-studded squad enough games during his first season in charge.

"Sometimes you play, sometimes you sit on the bench, sometimes you stay at home and aren't even in the squad," Ribery, who was shortlisted for the 2013 Ballon d'Or award, told German magazine Kicker.

"It was a new situation for everyone.

"Personally, I need a break after five or six games, not after just one."

But the timing of Ribery's comments did little to impress director of sport Matthias Sammer.

"The time to talk about these things is not just before a cup final," said Bayern boss Sammer.

Bayern are chasing the double having already won the Bundesliga title, but while Guardiola can win his fourth title since taking charge last June, a third defeat to Dortmund this season would mean a bad 2013/14 campaign for the Bavarian giants, especially having bowed out of the Champions League in the semi-finals.

"If we lose, it won't have been a good season for me any more," admitted Ribery, who has said he is fit to play, but unlikely to last the 90 minutes in Berlin.

Bayern are monitoring the Frenchman and Germany's Schweinsteiger, who has been unable to train this week, on a "day-to-day" basis according to Sammer.

"They are world-class players," he said.

"But whether they only play 20, 30 minutes or aren't even available won't be a factor on Saturday.

"Everyone must be willing, in a sporting sense, to die for each other."

This will be the 71st German Cup final and the 20th time Bayern are involved.

Dortmund are looking for their fourth cup final victory while Bayern have lifted the trophy a record 16 times and can add the domestic cup to their league, Club World Cup and UEFA Super Cup titles already collected this season.

Borussia lead this season's series between the two teams, which has been dubbed "Der Klassiker" with two victories to one having beaten Bayern in August's German Super Cup final and enjoyed a 3-0 league win in Munich in April.