Men's world number one Roger Federer had a short day at the Sony Ericsson Open in Miami when his opponent Robin Soderling of Sweden retired from their third-round match trailing 6-4 3-0 because of illness.

Federer served well but did allow world number 39 Soderling to break him in the fifth game of the first set.

"It's a big difference between not playing at all or playing one-and-a-half sets," Federer said.

"My opponent was a dangerous player. I think it was good for me to go out there and play today."

Federer, upset by American Mardy Fish at the Indian Wells semi-finals in his most recent prior event, will next face Argentina's Jose Acasuso, who eliminated Israel's Dudi Sela 6-4 6-4.

The newly-engaged Andy Roddick, with fiancé Brooklyn Decker watching, was tested by qualifier Ivo Minar of the Czech Republic before winning 7-6 6-4.

Roddick won the first set on his second set point in the tiebreak when world number 86 Minar's backhand hit the top of the net and landed wide.

Roddick was up a service break in the second set, but allowed Minar to level in the eighth game.

"Whenever you play someone who's won I think five matches in seven or eight days, including quallies [qualifiers], he's got to be hitting the ball well," Roddick said.

"He plays pretty high risk, and a lot of times there's not a lot you can do besides let him take his swings and hope eventually he might punch himself out."

Roddick now meets Frenchman Julien Benneteau who defeated Australian Open runner-up Jo-Wilfried Tsonga 6-3 6-3 in another third-round match.

In other matches on the men's side, Russian fourth seed Nikolay Davydenko reached the last 16 by defeating Italy's Simone Bolelli 6-7 7-5 6-1 and will next face Croatian wild card Mario Ancic.

Reuters