Miami - Andy Murray said Thursday that his health and fitness are fast-improving after last month's virus scare as the Scot fourth seed prepares for his start at the Miami Masters.

For once, Murray is sleeping in his own bed in the pulsing South Florida metropolis, staying in the flat he bought last year.

"I've spent a lot of time here in the last year and a half or so, obviously training, and taken a couple of holidays here as well," said Murray, who devoted his December to fitness work in the area.

"It's obviously nice to get to stay in your own bed at the tournament. That doesn't happen too much throughout the year." But while he has all the home comforts, Murray is most relieved by his all-clear several weeks ago from doctors who first thought he might be suffering from glandular fever.

The 21-year-old had to quit in Dubai last month, heading home to Britain for tests. While weakened even after a week of rest, Murray then pulled up fine at the Indian Wells Masters, where he surprised himself with a finals appearance against Rafael Nadal.

"I was lucky I only had to play once back to back days before the final. Obviously I was recovering decent after the matches because I had some time. But he admitted: "I was expecting to feel pretty rough on the court and struggling with my breathing. I had put in a lot of hard work in December and had some reserves there.

"I feel this week coming in I'm much better prepared."

The Scot said that doctors had feared he might be suffering with glandular fever as was Roger Federer in early 2008.

"When I had the first batch of sort of tests done, I got told it's not glandular fever, and then the next morning I got a call saying this it could be. Then I was starting to panic a little bit.

"I was obviously pleased it wasn't that, because it's a pretty debilitating illness. I'm just happy I'm feeling good again."

While Murray awaits a second-round opponent after a bye, winners began filling out the draw at Crandon Park with the leading 16 seeds on both the men's and women's side getting free passes past the opening round.

American men split a pair as Chile's Nicolas Massu, Chile put out Ryan Sweeting 6-4, 7-6 (7-2) while John Isner of the US defeated Sergiy Stakhovsky of the Ukraine 6-4, 6-4.

On the women's side, Anna-Lena Groenefeld stopped US veteran Jill Craybas 6-4, 6-1 and American Alexa Glatch beat Swiss Timea Bacsinszky 6-4, 6-1. (dpa)