Tottenham boss Harry Redknapp has warned his club they must buy this summer.

Redknapp says they cannot afford to stand still.

"If you want to do it again, you've got to improve," he said. "These top teams are going to keep improving.

"Chelsea are not going to stand still. They are going to go out and improve their team because the owner does that.

"Man City are going to improve, Man United, Arsenal are already making plans to bring new players in, Liverpool. It's getting tougher.

"There are six teams, really.

"That six are going to be there unless somebody buys one of the clubs. If they can get a Russian owner to buy Wigan who's got billions then they could win the league, couldn't they?

"That's how silly the game is."