Arjen Robben is facing a fitness battle ahead of Bayern Munich's trip to Real Madrid for their Champions League semi final on Tuesday evening, according to reports. 

The 34-year-old limped out of the first leg in Germany in midweek after just eight minutes and was not part of Jupp Heynckes's heavily rotated squad that overcame Eintracht Frankfurt in the ​Bundesliga on Saturday. 

And according to ​FourFourTwo, the Dutchman is struggling to overcome the knock after training alone on Sunday afternoon as the Bavarians prepare for their trip to the Spanish capital. 

​Bayern Munich, however, will be buoyed by the news that both David Alaba and Javi Martinez are expected to return to action after taking part in full training. 

"The mood within the team is very, very good," the Austrian told the club's ​official website. "You can see in training how focused and concentrated we are.

"In the dressing room, you can tell how much we want it. We'll throw everything we have at it. I'll obviously keep doing all I can to stay on track [to play]."

Alaba's return will instil confidence into Heynckes after his replacement, Rafinha, found himself exposed on a number of occasions during the first leg; with the Brazilian's loose pass setting up the attack from which Marco Asensio netted the winner. 

Jerome Boateng, however, will not be able to overcome his hamstring issue, although is expected to return ahead of the World Cup this summer. 

​Real Madrid, meanwhile, have injury problems of their own, with Isco ruled out ​"for up to three weeks" after being withdrawn prematurely in Munich on Wednesday. 

Right back Dani Carvajal is another concern for Zinedine Zidane, with the Spaniard, similarly to Isco, failing to last the full 90 minutes in midweek.