PIRAEUS, Greece - Thomas Mueller scored twice and substitute Mario Goetze added another as Bayern Munich beat Olympiakos 3-0 in Group F of the Champions League on Wednesday, with the hosts falling apart late in the match that was marred by scuffles in the stands before kickoff.

The 26-year-old Mueller spotted goalkeeper Roberto off his line and expertly lobbed in the ball in the 52nd minute, laughing at the success of his opportunistic strike.

"I must say that we did have a bit of luck with that goal. It's not something we've ever tried in training," Bayern coach Pep Guardiola said.

The Bundesliga side easily held onto their advantage in the second half. Goetze added the second a minute from time with a diagonal shot past Roberto before Muller struck again from the penalty spot in injury time, after Kingsley Coman was brought down in the area.

Spanish referee Velasco Carballo handed out yellow cards to Muller and four others player in the match at Karaiskaki stadium that saw several spells of bad tempered play.

In brief clashes before the game, riot police used batons to confront a small group of Bayern fans. No arrests were reported.

The hosts took the early initiative but were lucky to reach halftime on level terms after Robert Lewandowski missed a string of chances, his header in the 26th minute cleared off the line by striker Ideye Brown.

Leandro Salino missed a chance to level for the Greeks as he sprinted toward goalkeeper Manuel Neuer in the 63rd minute, but he aimed his shot just wide.

In the other Group F match, Dinamo Zagreb claimed a surprise 2-1 win over Arsenal.

Guardiola is making his third attempt to win Europe's top trophy for the Bavarians, following his fabled run at Barcelona.

The Catalan coach is still missing Arjen Robben and Franck Ribery through injury, and fielded Goetze after he overcame muscle strain that kept him out of domestic action last Saturday.

"I'm very happy to be in charge of this team," he said. "It's very hard to win here so I'm very happy with every player and proud of them all."

Olympiakos coach Marco Silva said he was happy with his men despite the disastrous result.

"It was an unfair result because it was a balanced game. We were strong until the first goal and that's the kind of goal you cannot control," he said.

"Bayern were lucky at that moment and then everything changed."

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