The Bayern Munich squad flew back to Germany on Thursday the day after suffering a surprise defeat by Porto in the Champions League quarter-final first leg. A glum-looking Thomas Muller, Manuel Neuer and Pep Guardiola were pictured at the airport ready to board their flight back to Bavaria after their 3-1 loss at the Estadio Dragao on Wednesday. The defeat was the price the five-time European champions paid for a string of injuries and a tired squad that has not stopped playing, chief executive Karl-Heinz Rummenigge said. Thomas Muller, Xabi Alonso and the rest of the squad get off the bus at the airport before returning to Germany . A glum-looking Pep Guardiola prepares to board the flight in Portugal with his depleted squad . Goalkeeper Manuel Neuer and Guardiola make their way on to the plane as they return to Bavaria after defeat . Bayern, chasing a treble of domestic and European titles, travelled with only 15 outfield players to Portugal for their quarter-final first leg leaving injured Arjen Robben, Franck Ribery, Bastian Schweinsteiger and David Alaba, among others, behind. 'I am not prepared to criticise the team,' Rummenigge said in post-midnight banquet. 'There are 13 or 14 players who are at the moment healthy and have been playing three times a week.' Bayern have been cruising towards the Bundesliga title with a 10-point advantage as the injuries seem to hardly affect them domestically. Guardiola cannot believe it as he sees his side beaten 3-1 by Porto in the quarter-final first leg on Wednesday . Neuer looks exasperated as the German champions concede their second goal of the game after 10 minutes . 'But there comes a day when you are a little bit tired, when your legs feel heavy and when you lack some of your concentration,' Rummenigge said. A lack of concentration certainly contributed to the three goals they conceded, each coming from an individual defensive mistake. What had been for much of the season their strongest asset - Bayern conceded just four goals in their first 17 Bundesliga games - was on Wednesday their Achilles heel. Jerome Boateng, Xabi Alonso and Dante, all lost possession or control near the box, allowing the Portuguese to score. Colombian Jackson Martinez rounds Neuer with ease before slotting into an empty net to put Porto 3-1 ahead . Bayern boss Pep Guardiola looks perplexed as his side fall two goals behind during the early stages of the Champions League clash . 'We imagined it differently,' said keeper Manuel Neuer, who was lucky not to be sent off after bringing down Jackson Martinez for a third-minute penalty. 'We were not confident and did not create scoring chances. The other problem was the mistakes we made. You are punished in the Champions League for those. We know we messed up together but we have to keep going.' While Bayern are not used to losing, they have every chance to overturn the first leg deficit, with Ribery and possibly Schweinsteiger fit for the return leg in Munich on Tuesday. 'I am not fully dissatisfied with the team,' coach Pep Guardiola said. 'We tried everything but it is not easy against such a physical team. 'It is a complicated result but we will take a shot at it in the return leg and we will not give up that easily.'
Bayern Munich were beaten 3-1 by Porto in the Champions League .
Pep Guardiola and the squad returned to Germany on Thursday .
Karl-Heinz Rummenigge refused to criticise the players, blaming injuries .