United go to Spurs on Sunday.
I think Spurs have done well this season," said Sir Alex at Friday's pre-match press conference. "I've watched quite a few of their games and their form has been consistent. They're in good form and I think they'll challenge for the top four.
"Villas-Boas has Spurs in the way he wants them and I think there are signs they're playing how he wants them to play. That's what a coach wants to do - get his philosophy across. I think they'll challenge for the top four."