ANDY MURRAY is playing the best tennis of his career and ranks behind only Novak Djokovic in the race to win the French Open, according to former British No.1 Annabel Croft.

Murray's bid for victory at Roland Garros has gathered momentum after the Scot won his maiden clay-court title at the Munich Open earlier this month, before beating Rafael Nadal for the first time on the red sand to triumph at the Madrid Masters.

The world No.3 lost to Djokovic in the Australian Open final in January, but with Nadal struggling for form and Roger Federer uncomfortable on clay, Murray is arguably the Serb's greatest threat in Paris.

"I think Murray's tennis is at a level now where it's almost as high if not higher than when he won Wimbledon and the US Open," said Croft.

"Beating Nadal in Madrid was a really big win mentally for him because he's always looked up to Nadal, but he also knows Nadal is well, well beneath his best.

"Now he can always say he beat Nadal on clay and, in my mind, he's the second favourite going into the French Open.

"If he meets Djokovic I would have to pick Djokovic to come through because Djokovic has beaten Murray seven times in a row, so he has the edge over him.

"But if something happened to Djokovic along the way, I'd say Andy is next in line on current form."

Nadal's slump to world No.7 means he will not be one of the top four seeds at the French Open, where ATP rankings take priority over a player's past record in the tournament.

It means Murray may have to overcome both Nadal and Djokovic to even reach the final in Paris, but Croft says the former Wimbledon champion has developed a more attacking game to beat his biggest rivals.

"Murray has become a much more aggressive player and his movement is better because he's less restricted by those back problems," Croft said.

"He can get more rotation on the ball and he's so much more aggressive than he used to be. We always used to say Andy was a great defender, he frustrated people with his cat and mouse style of play, but he was more passive.

"Now you'd never say that about him. He goes after you and his weight of shot is frightening.

"He started from a point of 'you can't get this ball past me' and now he's added an extra layer of aggression on top.

"He's a formidable opponent - the whole combination is pretty potent right now."