US number one James Blake drew inspiration from Michael Phelps' world-record swim as he shrugged off a two-hour rain delay and an attack of nerves to open his Olympic campaign with a win on Sunday.

Blake, who watched Phelps' 400m medley win before taking the court, beat big-serving Australian Chris Guccione 6-3, 7-6 (7/3) in the first match to finish.

Athens bronze medallist Fernando Gonzalez of Chile eased past China's Sun Peng 6-4, 6-4 while Russian fourth seed Nikolay Davydenko overcame dangerous Latvian Ernests Gulbis 6-4, 6-2.

"It was very exciting. Sitting there this morning watching Michael Phelps set a world record was special to me because it made me realize how many people are inspired by him," said Blake.

"Now I'm in the position to have that opportunity, to go out there and get a medal for my country. Today was hopefully the first step towards that."

World number eight Blake, who missed Athens 2004 during a traumatic spell in which he broke his neck and lost his father, will face either Dominik Hrbaty or Thomaz Bellucci in round two.

The 28-year-old New Yorker flashed a cross-court forehand winner to set up the first-set break point and converted with an unplayable backhand return on 23 minutes against his Australian opponent.

He was frustrated in the second set by the 90th-ranked left-hander but raced to a 3-0 lead in the tie-break before wrapping it up with an ace down the middle on 72 minutes.

Blake said he felt unusually nervous before his first Olympic match with a place in history at stake.

"I tend to not really get nervous when I'm out on a tennis court, but today was a little different," Blake said.

"This is even different than a Davis Cup. Davis Cup is thrilling, exciting, definitely a little different. But out here was crazy."

The start was delayed for more than two hours by rain at Olympic Green Tennis Centre as temperatures cooled after days of complaints about heat. However, relative humidity remained at a strength-sapping 95 percent.

"It's about as humid as I've ever played in, and I live in Florida," Blake said.

"It's pretty sticky. You've got to keep your wristbands on and you've got to keep going to the towel.

"When I was changing sides there was plenty of sweat droplets on the court from Chris as well."

Outgoing world number one Roger Federer was scheduled for an evening start as he opens his bid for a first Olympic medal.

Federer has placed particular emphasis on the Olympics and is also looking to recover the top ranking from Spain's Rafael Nadal, who will be crowned number one on August 18.

The Swiss faces a tricky opener against Russia's Dmitry Tursunov but Nadal has the tougher draw with likely matches against Andy Murray and Novak Djokovic before the final.

The Olympics has attracted an unusually strong field with only Andy Roddick missing from the men's top 10.