Ribery, 31, who missed out on the Ballon d'Or earlier this year, has produced a string of below-par performances since Bayern were confirmed Bundesliga champions at the end of March with a record seven league games to spare.

The Frenchman put in an improved display when he netted in Bayern's 5-2 league win at home to Werder Bremen in Saturday's dress rehearsal for the semi-final, with Real holding a slender 1-0 lead from last Wednesday's first leg in Madrid.

But Guardiola said he needs Ribery, who joined Munich from Marseille in 2007, at his aggressive best to help Bayern's bid to reach a fourth Champions League final in five years.

"Franck Ribery is very important for us," said Guardiola, who is in his first season in charge of Bayern.

"He has been at Bayern longer than me and I am happy, of course, if he plays with energy and motivation.

"He sometimes needs an angriness and I am sure he will play very well tomorrow.

"He has this fighting spirit. He always wants to fight for the team, that's why the people love him.

"He is one of the most fantastic players in the history of Bayern."

Bayern failed to get a crucial away goal in Madrid, despite dominating the stats with 72 percent possession and firing in 18 shots on goal compared to Real's nine, and Guardiola says his side must be more effective.

"I love being in possession of the ball, it was the way I was trained to play the game," said Guardiola.

"We want the ball to create chances and I want us to be just as dominant as we were in Madrid, but more effective and aggressive, we must find the right balance."