Bayern Munich put their Champions League rivals on notice by producing an extraordinary first-half display to hammer Roma 7-1 at the Stadio Olimpico tonight.

The Italians were powerless as Arjen Robben's brace, strikes from Mario Gotze and Robert Lewandowski and a Thomas Muller penalty gave the Bundesliga champions the most convincing of half-time cushions.

Gervinho netted a consolation for the hosts after the interval, but Franck Ribery and Xherdan Shaqiri came off the bench late on to further the damage, which boosts Manchester City's chances of qualifying following their disappointing draw to CSKA Moscow earlier this evening.

It was vintage Robben on nine minutes when he cut inside from the right wing to bend a shot into the far corner and give Bayern the ideal start to an encounter against one of their rivals for a last-16 spot.

Things continued to get better for the German giants as Gotze exchanged passes with Muller to thrash beyond Morgan De Sanctis, before Lewandowski headed home Juan Bernat's cross on 25 minutes.

Roma, who are second in Serie A and held Man City in their last European match, were shellshocked when Robben got his second and Bayern's fourth after racing on to Lewandowski's through-pass.

A nightmare first half for the Italians was compounded when Kostas Manolas clumsily handled a David Alaba cross inside the box, allowing Muller to extend Munich's advantage further from the penalty spot.

Rudi Garcia's side at least showed some spirit to come out of the blocks quickly in the second half as Gervinho hit the post with a thunderous shot and then saw Manuel Neuer deny him from close range.

The former Arsenal forward's persistence was rewarded on 66 minutes when Radja Nainggolan delivered perfectly into the area for him to head past Neuer, but that reply only made Bayern angry.

Ribery, continuing his comeback from injury with another cameo off the bench, notched 10 minutes after his introduction by cleverly lifting the ball over De Sanctis after being released by Robben.

Another substitute joined the goalscoring party on 80 minutes, with Shaqiri hammering home the rebound after De Sanctis had parried Rafinha's shot as Bayern continued their 100% Group G record.

Roma are five points behind in third following their heaviest ever home European defeat, which was also Bayern's biggest away win in the competition, and will likely vie with City for the second qualifying place.