Rooney has failed to impress for United this season, scoring just two Premier League goals in nine appearances, raising doubts over the captain's ability to lead the line in Manchester.
World Cup winner Xavi, who left Barca for Qatari outfit Al Sadd in the off-season, believes it is time for the 30-year-old to play a deeper role.
"Personally I think Rooney still has much to offer, but maybe it's time for him to adapt," Xavi said.
"You get to an age and you can't play the game you once used to, you can't cover the ground you used to.
"But intelligent players adapt and there's no doubting Rooney has a very good footballing brain.
"Maybe it's time for a new striker at Manchester United, who can run for 90 minutes, but Rooney would be very dangerous in a deeper role. He has the vision and the passing range to play that role very well.
"If he can adapt, there's no reason why he can't play at the top level for another five or six seasons.
"But as a player you must admit to yourself your body is changing and can't do what it used to be able to do."
Xavi, who played under United manager Louis van Gaal when the Dutchman was at Barcelona, knows he can be ruthless no matter how big of a name you are.
"Wayne Rooney is a player I have admired for a long time," the Spaniard added. "He is an extraordinary player with extraordinary capabilities.
"Van Gaal does not respect names though. It doesn't matter if you are the best player in the world, if he wants to drop you from the team, then he will drop you from the team.
"I respect and like Van Gaal because he is honest and direct, and I like to deal with people like that, but it can be hard to listen to his harsh criticism at times. But if you do, it will ultimately improve you."
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