Bayern Munich veteran Arjen Robben admits he's out of their Champions League first-leg clash with Liverpool due to injury.

The Dutch legend has not appeared for the Bavarian side since suffering a thigh injury in November, with a problem with his sciatic nerve forcing several comeback attempts to be abandoned.

Robben has confirmed he will miss their trip to Anfield on Tuesday although he remains hopeful of working his way back to fitness ahead of the second leg next month.

"It's very, very frustrating," Robben told Bild. "We've tried everything, but for now it doesn't work.

"Unfortunately, that is the problem: we don't know what it is.

"It's really difficult.

"Twice I've almost returned to the team, and again there was a relapse."