Despite a blip against Stoke last weekend, Spurs have been in a sensational run of domestic form, having won 11 of their last 13 league outings.
This has seen Harry Redknapp's side climb to third spot in the table; five points behind second placed United and seven points adrift of leaders Manchester City.
Spurs also retain a game in hand over their rivals, and will have the opportunity to open a gap of five points over Chelsea when the sides meet on Thursday.
Ferguson certainly sees the White Hart Lane club as contenders to lift the title come May, while the United boss has also been impressed with the brand of football adopted under Redknapp.
"Tottenham have been the most impressive team," Ferguson told The People.
"They were unlucky last Sunday at Stoke but if they win their game in hand they are still in there.
"And for me, Spurs have been playing the best football in the Premier League for the last eight games.
"They look confident and dangerous and I have been very impressed with them.
"They have played some terrific football and they must be contenders now they are out of the Europa League - that will definitely help them."
He added: "When you look at the start of the season you expect the four to be there - ourselves, Chelsea, City and Arsenal but now Spurs are right in there without a doubt."