Former men's world number one Andre Agassi has tipped Novak Djokovic to become the first man since Rod Laver to win all four grand slams in a calendar year, saying the Serb has got what it takes to triumph at the French Open, Wimbledon and the US Open in 2015.

Speaking ahead of the Davis Cup tie between Great Britain and the United States, the eight-time grand slam champion that based on current form, world number one Djokovic is the man to beat for the rest of this tennis season.

"I don't want to start putting pressure on him [Djokovic] by just doing one interview, but before he won Australia [Australian Open 2015] I said there's a heck of a chance we're going to see the first time since [Rod] Laver someone win all of them in the same year. I think he's really capable of that," he said.

"He's playing at a level above everybody at the moment. I think he still has a lot of room for improvement and if Nadal doesn't get himself right for Paris, that will be his biggest stumbling block... I think he's looking at a pretty dominating year," he added.

Djokovic equalled Agassi's record of eight grand slam titles when he beat Andy Murray in the Australian Open final earlier in 2014. The next grand slam event is the French Open in May, a tournament Djokovic has never won, losing in the final to Rafael Nadal in 2012 and 2014.

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