Bayern Munich's Thomas Mueller (L) and Mario Goetze celebrate Mueller's goal against Olympiacos during their Champions League group F soccer match at the Karaiskakis stadium in Piraeus, near Athens, Greece, Sept 16, 2015. [Photo/Agencies]

ATHENS - Two goals from Thomas Mueller and one from substitute Mario Gotze helped Bayern Munich kick off their Champions League campaign with an impressive 3-0 victory over Olympiakos Piraeus at the Georgios Karaiskakis stadium on Wednesday.

Bayern controlled possession for long spells in an entertaining Group F encounter with Robert Lewandowski a constant threat before Mueller beat Olympiakos goalkeeper Roberto with what looked like an intended cross from out on the right flank after 52 minutes.

Olympiakos battled manfully in front of their frenzied supporters with Nigerian striker Ideye Brown going close on a couple of occasions.

But Marco Silva's side could not find an equaliser and it was Bayern who struck again with two goals in quick succession in the closing stages from Gotze and a Mueller penalty as the hosts ran out of steam.

The win means Pep Guardiola's Bayern maintained their 100 percent start to the season with a sixth win in all competitions.

"We kept the ball, we created chances and we did not leave much room for Olympiakos to hurt us," Guardiola said.

"I'm delighted for Mueller, he has the quality to score goals like that but I'm pleased with the whole team today."

Olympiakos coach Silva was not convinced that Bayern were worthy winners.

"Without doubt the result was unfair on us," he said. "The match was evenly balanced in the first half and we were also unlucky in the way the first goal was scored."

It was the hosts who had the first clear sight of goal in the 20th minute with Felipe Pardo's deflected cross finding Brown all alone in the area.

Yet the Nigerian's downward header from close range lacked power and was comfortably saved by Manuel Neuer.