Clough backs five-star United

Nani and Darron Gibson effectively sealed a quarter-final tie at either Swansea or Fulham before half-time, with Cristiano Ronaldo and Danny Welbeck wrapping up a 4-1 win. It means the world champions are just three victories away from winning England's oldest cup competition and are well-placed to claim trophies on all five fronts this season.

"If anyone can do it they can," claimed Clough.

He added: "If United had played Arsenal, Liverpool or Chelsea in that form they could have put four past them, they were that good.

"We have played against them three times this season now and this was the best they played."

Once Nani had opened the scoring with a magnificent 20-yard effort, United never looked like being headed.

But Sir Alex Ferguson was more than slightly confused by the furore that accompanied a disallowed Ronaldo goal after the opener.

Having failed to raise his flag immediately as Ronaldo chased Giggs' flick, the linesman then made his decision after the Portugal superstar had found the net.

"The linesman created his own confusion because he went so long, until after the goal had been scored, to say it was offside," said Ferguson.

"He said he was waiting to find out whether Ryan had touched it. Nevertheless, Ronaldo was still in an offside position. I have no complaints about the actual decision. It was the fact he waited so long. I did not understand the explanation."