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."
Robben twice failed to pass to Lewandowski in the second half.
Lewandowski later told Sport Bild: "I won't comment on it. You've all seen it."
Pep Guardiola told the postmatch news conference that there was little he could do to change Robben'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."