Roger Federer survived a wobble in his opening Olympics singles match on Saturday while fellow Wimbledon champion Serena Williams stormed through to join him in the second round on a day in which several seeded players bowed out.
Top men's seed Federer of Switzerland made tough work of his first round clash against Colombia's Alejandro Falla, throwing away three match points in a nail-biting second set before eventually prevailing 6-3 5-7 6-3.
Williams, watched by US first lady Michelle Obama, fourth seed Williams dispatched Serbian former world number one Jelena Jankovic 6-3 6-1 on a packed Centre Court in just 61 minutes.
"It was great seeing Michelle there. It just made me want to play better and I felt even better. We're here for our country and to play well. I loved her dress, which is always nice. She is always looking good," Williams said after the match.
Federer's battle captivated the animated crowd, who had to get used to the unfamiliar Wimbledon sight of competitors wearing colours rather than white as well as music blaring from the speakers as the players warmed up.
"I never stopped believing, kept on pushing. Even though he got back a break in the third set, that obviously also got my nerves going because the margins are very small at that point," said Federer, who now faces France's Julien Benneteau.
"I'm happy I found a way to tough it out really."
While Federer and Falla stuck to white shorts, they both wore brightly coloured t-shirts, with Federer in Swiss-flag red and his opponent sporting yellow.
On the grassy mound by Court One, dubbed Henman Hill after former British number one Tim Henman, there was a party atmosphere as fans decked out in national flags were treated to a 15-minute show by about 50 flash young dancers followed by a performance from British pop music duo the Pet Shop Boys.
The first match up on Wimbledon's Centre Court, where Williams and Federer raised trophies less than three weeks ago, saw men's sixth seed Tomas Berdych of the Czech republic knocked out 6-4 6-4 by Belgium's world number 75 Steve Darcis.
Other first-day upsets saw women's fifth seed Australian Samantha Stosur lose 3-6 7-5 10-8 to Spain's Carla Suarez Navarro, while Navarro's countryman and men's number 14 seed Fernando Verdasco fell to Uzbekistan's Denis Istomin 6-4 7-6.
"I am immensely disappointed," Verdasco said. "I have played him three times before and have won each time but I came here not 100 percent fit."
"I am not in the doubles so I am going home. It has been a long season to finish and I am going to try to rest and sort these problems out."
China's 10th seed Li Na was beaten by Slovakia's Daniela Hantuchova 6-2 3-6 6-3.
Also out of contention before even arriving in London is Germany's Wimbledon quarter-finalist Philipp Kohlschreiber, who has pulled out through injury after losing the Kitzbuehel Cup final in Austria to Dutchman Robin Haase on Saturday.
In the doubles, top seeds Bob and Mike Bryan of the United States reached the second round with a 7-6 6-7 6-3 win over Brazil's Thomaz Bellucci and Andre Sa.
The other sibling duo in the men's event, Britain's Andy and Jamie Murray, lost 5-7 7-6 7-5 to Austria's Juergen Melzer and Alexander Peya.
British number one Andy, who lost the Wimbledon final to Federer this month, will be back in action in the singles on Sunday, beginning his gold medal quest against Switzerland's Stanislas Wawrinka in the second match on Centre Court
Number two seed Novak Djokovic of Serbia will play Italy's Fabio Fognini on Court One while women's top seed Victoria Azarenka of Belarus takes on Romania's Irina-Camelia Begu.