Bayern Munich coach Pep Guardiola has come under fire from his Bundesliga peers for fielding a weakened team ahead of Wednesday's Champions League quarterfinal, second leg at home to Manchester United.

The European champion suffered its first German league defeat in 18 months on Saturday, abruptly ending its record 53-match unbeaten Bundesliga run with a 1-0 defeat at Augsburg.

Guardiola paid the price for naming three teenagers in his starting lineup as he made seven changes from last Tuesday's 1-1 draw at Manchester United in the first leg.

With the German league title already secured with a record seven matches to spare, Guardiola defended his decision to rest his stars for United.

"The game against Manchester is (effectively) a final, it comes down to life or death now," said the Spaniard.

"If it (the Augsburg game) had been important, Philipp (Lahm), Franck (Ribery) and Arjen (Robben) would have played.

"But (this season's) Bundesliga is over, it is in the museum at Bayern Munich and will remain there forever."

Guardiola's peers were quick to criticize his decision to hand reserve team wing backs Ylli Sallahi and Mitchell Weiser their Bundesliga debuts while Pierre-Emile Hoejbjerg was named on the left wing.

"It's not OK for the league," said Eintracht Frankfurt coach Armin Veh. "Of course, anyone can lose against Augsburg, but if you look at the starting line-up I must say: you reap what you sow."

Guardiola fielded a bench in Augsburg containing internationals David Alaba, Thomas Mueller, Mario Goetze, Jerome Boateng and Dante.

According to Werder Bremen coach Robin Dutt, a cursory glance at Bayern's replacements gave the impression "as if the Bundesliga was just a bit of leisure activity".

Horst Heldt, third-placed Schalke 04's general manager, said Guardiola and Bayern had done the Bundesliga a disservice by clearly prioritizing the Champions League.

"Bayern always send out a few clever sayings which the rest of us are expected to take on board," he told German radio.