Juan Bernat and Franck Ribery missed Bayern Munich's final training session ahead of their crucial Champions League clash and against Porto on Tuesday.
Bastian Schweinsteiger trained with the team, however, and it is reported that Arjen Robben could make a surprise return to the squad too.
Bayern host Porto at the Allianz Arena on Tuesday night needing to overcome a 3-1 first-leg deficit to reach the semifinals for the fourth consecutive season for the first time in the club's history.
Pep Guardiola has seen his squad suffer from injuries to several key players in recent weeks. Javi Martinez, David Alaba and Medhi Benatia are all unavaible for selection, while Philipp Lahm and Thiago Alcantara are slowly finding their feet after long spells on the sidelines.
During his prematch news conference on Monday, Guardiola said that only a miracle would see Ribery play any part after being out for a month with an ankle injury. There is more chance that Spain defender Bernat will feature while Schweinsteiger, who last played in the 1-0 win at Borussia Dortmund in early April, will be in the squad.
Bild named Robben as a surprise option, with the Netherlands winger training individually on Monday. The 31-year-old has been ruled out with an abdominal muscle injury since late March, and has previously said that he will not return before the DFB-Pokal semifinal clash with Dortmund next week.
Meanwhile, Bayern released a video calling all fans in the Allianz Arena to create a special atmosphere inside the stadium as they look to recover from the shock defeat in Portugal last week.
"It's going to be tough -- but together, we can do it! This evening, FC Bayern will attempt to overturn a 3-1 deficit from the first leg against FC Porto and reach the semifinals. And that needs total support from you, the loyal fans!" they said on their website. The video includes statements from Philipp Lahm, Thomas Muller and Arjen Robben.