Summer is over. That only means one thing: the Champions League is back. This year’s joint favourites, Barcelona and Chelsea, have fast become bitter rivals in this competition. That rivalry is certain to intensify since they were drawn into the same group at this early stage of the tournament. The format is as follows: 32 teams contest the group stage, divided into eight groups of four. The group winners and runners-up advance to the knockout stages, the eight third-placed teams move into the UEFA Cup third round, and the eight fourth-placed teams are eliminated. Here is an overview of all the groups with predictions on who we expect to win each group.Group A: Barcelona (-118), Chelsea (+125), Werder Bremen (15/1), Levski Sofia (250/1)Maybe the Chelsea-Barcelona rivalry won’t be quite as intense at this early stage. Both teams will advance from this group and there is a good chance they will meet again at a later stage of this competition. Chelsea look noticeably shakier this year. Their previously impenetrable defence looks slightly more lax. That will bode ill for the Blues. But unlike the past few years, with two Premiership titles under their belt, this season Jose Mourinho’s explicit goal is…