Ahead of tomorrow night's Champions League final between the two clubs, Xavi heaped praise on Barca's opponents for what they have done in recent seasons.
"What Manchester United have done over the years has so much merit," he said.
"They have been playing for many years at an extraordinary level, they have won many trophies, they have been competing consistently, getting to Champions League semi-finals and finals.
"They are on a spectacular level; all the footballers are at an extraordinary level.
"What Ferguson has done, what Scholes and Giggs have done - to be competing like they have, year after year, has a lot of merit."