Britain's Andy Murray leaves the water after taking a brief swim after a photo opportunity in which he posed with the champion's trophy on the beach near the stadium where he defeated Spain's David Ferrer in their men's singles final match at the Sony Open tennis tournament in Key Biscayne, Florida March 31, 2013.  [Photo/Agencies]

MIAMI - An exhausted Andy Murray credited his mental strength and physical freshness for his tie-break victory over David Ferrer in the Sony Open final on Sunday after a gruelling two hour, 45 minute battle.

"It was a brutal, brutal match. Both of us were kind of on our last legs," Murray told reporters after his 2-6 6-4 7-6 win.

"It was a good job it wasn't a best-of-five-set match, because I don't know how the last few sets would have ended up.

"It was one of the toughest matches I have had to play in a Masters Series, for sure," added the Scotsman who will move to number two in the world, above Roger Federer, in Monday's latest ATP world rankings.

The match, played at mid-day in South Florida heat and humidity, became a war of attrition with neither player near their peak in terms of shot-making but both doggedly sticking at the task.

"I showed good mental strength to get through that match, because it easily could have slipped away from me," said Murray.

"It was a big match for both of us, and I think that showed in some of the way that we played.

"We didn't play necessarily our best tennis. I was up a lot and couldn't close the match out. Matches like these ones are tough, because, you know, the humidity here is brutal," added the U.S. Open and Olympic champion.

Murray is acknowledged as one of the sport's true fitness fanatics, spending his off-season in Miami working out but he said his physical condition at the end of the contest owed more to his scheduling.

"I think just general freshness, really. I think being fresh helped even though the tennis wasn't great," he said. "I just managed to get over the line in the end."

Ferrer was left regretting his decision when on championship point, 5-4 up against Murray's serve, to challenge a Murray shot rather than play it.

The ball was ruled in and the Scot went on to take the game into a tie-break which he won 7-1.

"I chose my decision in that moment. It's a bad moment now and don't want to think anymore about that. I want to forget it as fast as possible," the Spaniard told reporters.

Ferrer's determined display led Murray to urge greater respect for his opponent, currently ranked fifth in the world.

"I don't think he gets the respect that he deserves within the game. He's been in the top five in the world now for at least three years.

"He's improved his game every single year. That takes, you know, a great attitude to be able to do that," said Murray.

"Providing his body holds up, he'll be around the top of the game for as long as he wants or he can, because he's a very, very, good tennis player and has a great attitude."