Andre Agassi believes Andy Murray’s ‘tortured spirit’ will see him land multiple Grand Slam titles after marking his comeback from injury with victory in Valencia.

Murray – Britain’s number one – won his sixth title of the season in Spain on Sunday with a 6-3, 6-2 victory over Russian Mikhail Youzhny.

Following Juan Martin Del Potro’s US Open victory in September, Murray is now the only player in the world’s top five yet to win one of tennis’ four top prizes.

But Agassi – Murray’s childhood idol - said: “I think he’ll win multiple grand slams. It’s been my prediction for a while.

“This year was disappointing for him. I know he was on the verge in a couple of grand slams with the hopes of winning. Once he does one, the floodgates will open.

“He has a self-inflicting tortured spirit about him when he’s on the court and I think in the last year and a half he’s really learned how to use it.”