The director hopes that Barca's superstar winger will take his anger out on Manchester United...
"If Messi is annoyed he becomes very dangerous," Begiristain said, quoted by the Associated Press.
"I hope he's annoyed. There are a lot of comparisons and that annoys him and motivates him a lot."
And with the looming opportunity to secure a treble this year, Begiristain has called on the Blaugrana to gather their strength and end the season on a high note.
"We have done very well to get to here now, and now it is time to finish off the work of a whole season," he said.
"This is a unique opportunity in the history of the club. We need to enjoy it and focus to achieve it."
Stephen Crawford, Goal.com