|Federer salutes the crowd after his first round win [GALLO/GETTY]
Rafael Nadal and Roger Federer took their first steps towards Olympic gold with contrasting victories in the men's singles, whilst world number six Andy Murray suffered a shock first round defeat to Chinese Taipei's Lu Yen-Hsun.
Top seed Federer shook off his recent indifferent form with a commanding 6-4, 6-2 defeat of Russian Dmitry Tursunov. Nadal, in contrast, dropped a set to Italy's Potito Starace for the first time before winning 6-2, 3-6, 6-2.
Nadal, the French Open and Wimbledon champion, will succeed Federer as world number one when the latest rankings are published next week, regardless of what happens in Beijing.
"Sometimes it plays a trick in your mind where you think maybe you're not playing that well, but it's actually not the case," Federer said, clearly relieved to be up and
running at the tournament after a difficult five weeks.
"I played well, hit some great winners, got some good balls back. I was playing very solid."
Nadal opened proceedings on Centre Court clad in the red and yellow of his national flag as Prince Felipe of Spain looked on.
After rattling through the first set with some flashing winners he was pegged back when Starace took the second set with some resilient tennis of his own.
Nadal had the crowd gasping with one incredible pick-up from a Starace drop shot early in the decider as he regained his momentum.
A dispirited Starace eventually dumped a drop shot into the net to hand Nadal his first victory in Olympic tennis.
Sunday's rain allowed just nine completed results and organisers crammed 65 matches into Monday's manic order of play meaning a feast of action at the nine-court tennis complex.
In the women's singles, American Serena Williams wasted little time reaching the women's second round, polishing off Olga Govortsova 6-3, 6-1 in a match interrupted on Sunday.
Williams, however, seemed annoyed with her schedule. "I felt like I should have had today off but it was good practice," she said.
"I wanted to go to the market today but we have to play so many matches."
Williams was joined in the second round by French Open runner-up Dinara Safina, one of four Russian medal prospects in the singles.
Australia's Lleyton Hewitt, the former world number one, beat Swedish veteran Jonas Bjorkman 7-5 7-6 to set up a second round tie with Nadal.
Britain's Andy Murray cut a frustrated figure as he was out-played by an opponent ranked over 70 places below him.
Murray will have a chance to redeem himself later in the Olympics when he and brother Jamie open their doubles tournament with a first round match against Daniel Nestor and Frederic Niemeyer.
Meanwhile, defending men's doubles champions Fernando Gonzalez and Nicolas Massu fell at the first hurdle in their bid to retain their title.
The unseeded Chileans were beaten 7-6, 6-4 by Russian team Dmitry Tursunov and Mikhail Youzhny.
In Athens they became national heroes when they won the doubles event to earn Chile its first gold medal at an Olympic Games. Massu also won the singles there.
Massu and Gonzalez still have medal hopes here as they both survived their opening round singles matches.
Massu beat Steve Darcis on Monday while Gonzalez beat China's Sun Peng.