Robert Lewandowski showed his frustration with Arjen Robben during the victory over Stuttgart. Lennart Preiss/Bongarts/Getty Images

Bayern Munich winger Arjen Robben has insisted that he and teammate Robert Lewandowski "need to stay critical with each other" amid claims of a poor relationship between the pair.

German sports weekly Sport Bild reported on Wednesday that "it is no secret in the team that Lewandowski and Robben avoid each other in the dressing room" and there were signs of tension during Bayern's 4-0 win over Stuttgart on Saturday.

Robben -- now enjoying a run in the side after a series of injury problems dating back to last season -- twice failed to pass to Lewandowski in the second half, with the Poland striker complaining to his teammate on the pitch.

Lewandowski later told Sport Bild: "I won't comment on it. You've all seen it."

Robben, meanwhile, told the weekly magazine that it was necessary for the pair to be free to criticise one another and added: "There were a few situations in the first half where he could have passed the ball too."

While Bayern sporting executive Matthias Sammer defended Robben, saying "it's not a problem when a player mopes around," coach Pep Guardiola told the postmatch news conference that there was little he could do to change the Netherlands international's approach at this stage.

"That's Arjen Robben -- his mentality," he said, before joking: "I am a good coach, but not good enough to change Arjen Robben's mentality at 31 years old."