Defending champion Andy Roddick made a shock early exit from the Sony Ericsson Open on Saturday, suffering a second round loss to Uruguayan Pablo Cuevas 6-4, 7-6.
The world number eight, struggled physically and needed medical treatment during the second set, said that he was likely suffering from a lingering bronchial infection.
"I had a little trouble breathing out there today. I've had something for a little while but I'm going to have it checked out when I get home," the American told reporters.
Roddick was broken in the seventh game as 67th-ranked Cuevas took charge and although he battled on in a tight second set, he looked sluggish and bowed out in the tiebreak with consecutive forehand errors.
"I'm just frustrated. You don't like going out there with less than what you have got and I feel like I have been doing that a lot," he said.
"It's not like I'm super mad because I had chances or lost or didn't play. It's just frustrating," he added.
The win was the first for Cuevas against a top 10 ranked player and left the tournament without another drawcard after Britain's Andy Murray was defeated by U.S. qualifier Alex Bogomolov on Friday.
Number one seed Rafael Nadal had no such problems, however, and was satisfied with his 6-4, 6-4 win over Kei Nishikori of Japan.
"I'm very happy about how I played. I think I played at a high level tonight," Nadal said. "The feeling was better than last week, so that's important. My serve worked very well at the end of the match," he added.
Leading 2-1 in the first set, Nishikori failed to convert on two break opportunities and Nadal promptly broke the Japanese player in the ensuing game. In the eighth game, Nishikori again failed to convert on two break points.
Nadal broke Nishikori in the opening game of the second set and held serve to close out the match.
Third seed Roger Federer also advanced, enjoying a routine 6-3, 6-3 win over Czech Radek Stepanek earlier on Saturday.
The victory took Federer alongside Pete Sampras with 762 career wins, equal seventh overall. Jimmy Connors tops the list with 1,241 wins.
"It's a funny stat," the Swiss said. "But it shows how long I have been around already, how much I've won all around the world and on all the different surfaces."
Federer, seeking his third Miami title, was ruthless, converting all three of his break point chances.
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