Murray fit to break top three

The 21-year-old was in superb form during the Miami tournament, dropping just two sets on the way to the final which he convincingly won 6-2 7-5 despite the blistering hot conditions.

"(It) just gives you more confidence going into the matches knowing you're in good shape," he said.

"I think just mentally it makes a difference. Even if you're struggling, you know your opponent is going to be feeling the same, as well.

Whereas the heat may have slowed Murray in years gone by, the Scot looked unfazed as he secured a win that moves him to the brink of passing Djokovic into third place in the world rankings.

Already many pundits believe Murray is worthy of that status, even if the rankings do not yet suggest it, and his recent form would back such claims.

Since losing to Rafael Nadal in the quarter-finals at Wimbledon last year Murray has returned a win-loss record of 57-7 - the best mark on the ATP tour ahead of the world number one Nadal's 50-7.

And Murray believes a key reason for his all-conquering form can be simply be put down to the fact he is physically better prepared.

He added after Sunday's win: "Whereas before sometimes you could get tired and look over at the other side and the opponent seems fine. A match like today, there's obviously points...I mean, it was hot out there.

"A few long rallies and stuff I would be a little bit out of breath. I could look down the court and see him struggling, as well."