Former Manchester City defender Jerome Boateng scored in stoppage time as Bayern Munich opened its UEFA Champions League campaign with a last gasp win over the Premier League champions on Wednesday night while elsewhere, AS Roma and FC Porto eased to big wins over CSKA Moscow and BATE Bosrisov respectively.

Bayern dominated proceedings for large periods but were unable to find a breakthrough, with Thomas Mueller hitting the side-netting as early as the first minute, before City goalkeeper Joe Hart kept out efforts from Mueller, Mario Goetze and David Alaba as the 2013 European champions pressed for the opener.

Hart would further deny Goetze, Rafinha and Boateng in the second half as it increasingly looked like the England international would single-handedly earn City a point from the Allianz Arena, until stoppage time when Boateng controlled the ball and struck a fierce effort past him for the win.

The win put Bayern in second place however, behind Italian side AS Roma that cruised to a 5-1 win over Russian champions CSKA Moscow in the other Group E match played at the Stadio Olimpico in Rome.

Ivorian forward Gervinho put Roma ahead after six minutes before setting up Juan Iturbe for the second four minutes later. Roma captain Francesco Totti then set up Maicon for the third after 20 minutes and Gervinho to make it 4-0 10 minutes later.

A Sergei Ignashevich own goal ensured the Italians scored five goals in the Champions League for the first time while Nigerian forward Ahmed Musa scored a late consolation for the visitors.

Elsewhere in the Champions League on Wednesday night, Algerian international Yasine Brahimi scored a hattrick for FC Porto in the 6-0 demolition of BATE Borisov in a Group H match at the Estadio Dragao, with Athletic Bilbao playing out a goalless draw in the other Group H match.