Xavi insists the PSG attacker would improve his LaLiga title winners.
He told Sport, "Right now there's no doubt [Messi] would help us.
"Leo could play in various positions: false nine, winger, in midfield, or even as a no.10, arriving to play the final ball.
"He has become almost a central midfielder, almost an attacking midfielder, and he has that ability at the end of the day.
"At the World Cup we saw Messi at an unbelievable leve.
"I think he has many years left in him, at a good level."
Xavi also said: "For me it makes sense. There's no doubt that if Messi returns it would help is in a football sense.
"I've told the president that. I have no doubt...because he is still a player who can make the difference, he's still hungry, he's a winner, a leader, and he's also a different player.
"We don't have a Barcelona team with the talent of 2010...[Messi] would bring talent, the final ball, set pieces, goals..."