Manchester United legend Rio Ferdinand has taken aim at Liverpool's defence.

United host Liverpool on Sunday at Old Trafford.

"I think we've got the best managers in the world here in the Premier League," Ferdinand told United's official website.

"Other than maybe Carlo Ancelotti, Diego Simeone and Zinedine Zidane, I think we've got the best, the most entertaining and the biggest personalities all here.

"Jose Mourinho is, of course, one of them and so is Jurgen Klopp, who I have to say has been a breath of fresh air since coming to England.

"The way he sets his teams up, from Dortmund to this Liverpool team, is exciting. They're great to watch.

"They play with verve; they have a direct, aggressive, quick, attacking mentality and attack in numbers.

"No matter which club you support, Liverpool under Klopp are a very good team to watch and that makes them dangerous.

"They're going to win games 3-2 or 4-3 and while I think, defensively, they have an Achilles heel, if they're going to outscore teams then they're going to be a big threat."