Bayern Munich coach Pep Guardiola says no defence in the world is capable of stopping Barcelona superstar Lionel Messi.
Guardiola is set for an emotional return to Camp Nou for Wednesday's UEFA Champions League semi-final first leg.
The 44-year-old spent 11 years as a player at Barca, before returning as coach where he oversaw one of the greatest eras of success in the club's history between 2008 and 2012.
During his four-year spell in the dugout, Barca won La Liga three times, and the UEFA Champions League and Copa del Rey on two occasions.
Argentina international Messi was the driving force behind that team, but this time he will provide a headache for Guardiola who is attempting to mastermind a way past Luis Enrique's side.
"If Messi is in top form, no defence can stop him," Guardiola said. "There is no system to stop Messi. He's too good.
"You just have to try to limit him in another way - stop the ball reaching him, but even then, you can't stop him."
Guardiola also stated that there is far more for Bayern, who decimated Barca at the same stage in the 2012-13 season, to worry about than just Messi.
"It's very difficult to find any weaknesses with talent like this," he added. "We're going to try to perform as well as we can. We're going to try to better than we usually are. You know the level of respect I have for these players and for Barcelona.
"I think that they have the advantage because I know them but when you think you might know what these players are going to do they do something different.
"I know that from a defensive standpoint it's really impossible to stop them. We can't stop them."
