All was looking so positive for Bayern Munich ahead of their eagerly anticipated Champions League semifinal against Barcelona. Bayern had mounted a spectacular comeback in their quarterfinal, beating Porto 6-1 in the second leg, before five days later clinching their third successive Bundesliga title. Going into Tuesday’s DFB-Pokal semifinal with Borussia Dortmund, the treble was very much on, while manager Pep Guardiola was relishing once again being able to call upon key figure Arjen Robben following five weeks out with injury.

But in the second half of that fixture at the Allianz Arena, things spectacularly unraveled for the Bavarians. First Dortmund cancelled out Bayern’s opener, then Robben, only 16 minutes after making his return off the bench, was forced to limp off with his head in his hands. More misfortune was to follow. In extra-time, Robert Lewandowski took a hefty blow to the head from Dortmund goalkeeper Mitchell Langerak, leaving him unable to take part in a penalty shootout, which Bayern lost without converting a single spot-kick.

Their treble dream already gone, Bayern’s Champions League hopes were thrown into serious jeopardy by the revelations that Robben had torn a calf muscle, while Lewandowski had his nose and jaw fractured. The Dutch winger was instantly ruled out until the end of the season, although both Bayern and the player are hopeful that Lewandowski will be able to take part against Barcelona in the first leg at the Camp Nou next Wednesday.

It is still far from ideal preparation as Bayern attempt to avoid a repeat of their chastening defeat in last year’s Champions League semifinals to Real Madrid. And it also again brings the issue of Bayern’s ability to keep their players fit into the spotlight, two weeks after the club’s long-time doctor Hans-Wilhelm Müller-Wohlfahrt stepped down stating that the medical department had been made a scapegoat for the 3-1 defeat to Porto. Franck Ribery, David Alaba and Holger Badstuber were already on the sidelines, with only Ribery having a chance of returning to take on Barcelona.

It is Robben who is undoubtedly the biggest loss. When Guardiola first arrived it was reasonable to doubt whether the Dutchman would have a future at Bayern, given his individualistic style seemed in contradiction to Guardiola’s possession-based team ethos. Instead Robben has been Bayern’s pivotal player, particularly this season, scoring 17 goals and contributing nine assists. So often his direct approach has added much needed variety to Bayern’s passing game.

The task facing Bayern would be sizable, even were they to have the luxury of a fully-fit squad. While Bayern were enduring a night to forget against Dortmund, Barcelona were putting on a breathtaking show to beat Getafe 6-0. Lionel Messi, Luis Suárez and Neymar all found the net to take the star trio’s goal total for the season to an extraordinary 102 in all competitions. Not only are they undoubtedly the most dangerous front line in the world today, but they are fast moving up the ranks of the greatest in history. At the same time, Barcelona’s defense is appearing as resilient as it has done in several seasons, certainly since before Guardiola left the Camp Nou in 2012.

With domestic dominance now effectively taken for granted, it is in the Champions League where Bayern and Guardiola are judged. A second-straight semifinal defeat after taking over from treble-winning Jupp Heynckes would be a significant disappointment. But if Bayern are to go all the way this year then they will have to do it the hard way. Still, the 6-1 win over Porto, achieved without Robben, Ribery, Alaba, and Bastian Schweinsteiger, showed that Guardiola’s ability to devise a winning game plan can never be ruled out.