Venus Williams Five-time Wimbledon champion Venus Williams suffered her worst All England Club defeat in 15 years, but draw cards Novak Djokovic, Roger Federer and Maria Sharapova powered into the second round.
Williams lost 6-1, 6-3 to 79th-ranked Russian Elena Vesnina in what was the 32-year-old's first opening round loss since her 1997 debut.
But the former world number one -- the champion in 2000, 2001, 2005, 2007 and 2008 -- believes she can still compete at the top level despite her ranking having slipped to 58 after a six-month absence fighting serious illness.
"There's no way I will give up just because I have had a hard time in the first four or five friggin' tournaments back. That's not me," said a fiesty Williams at a post-match news conference.
When asked if she will play at Wimbledon in 2013, she was adamant."Sure," she said. "I don't have time to be sorry for myself."
Monday's defeat was just Williams' fourth loss at the first round stage of a Grand Slam against 52 wins.
Vesnina, who had lost in the first round of nine of her last 10 Grand Slam appearances, will next face Polish third seed Agnieszka Radwanska who enjoyed a 6-3, 6-3 win over Slovakia's Magdalena Rybarikova.
While Williams was heading for the exit, another crowd favourite, Kim Clijsters, was rolling back the years with a 6-2, 6-4 win over Serbian 18th seed Jelena Jankovic.
Clijsters, unseeded this year and playing her last Wimbledon before retirement, will face Andrea Hlavackova of the Czech Republic.
The 29-year-old Belgian, playing just her second event since March, was untroubled against the error-plagued, former world number one Jankovic who lost in the first round for a second successive year.
"When I saw the draw I knew it was going to be a tough one but at the same time I really looked forward to playing her," said Clijsters, after her eighth win in nine meetings with Jankovic.
Sharapova, who completed a career Grand Slam with victory at the French Open, eased past Australia's Anastasia Rodionova 6-2, 6-3.
Sharapova, the 2004 champion, will face Bulgaria's Tsvetana Pironkova, who reached the semi-finals in 2010.
Top seed Djokovic, opening business on Centre Court, reached the second round with a 6-3, 6-3, 6-1 win over Spanish veteran Juan Carlos Ferrero.
Djokovic, 25, playing for the first time since his French Open final defeat to Rafael Nadal, will next face America's Ryan Harrison.
"It's a very unique feeling to walk out first on Centre Court," said Djokovic, whose hopes of becoming just the third man to hold all four Grand Slam titles at once were shattered by Nadal in Paris.
"I think this is the only tournament that actually allows you to have information 12 months in advance when you're playing."
Third seed Federer beat Spain's Albert Ramos 6-1, 6-1, 6-1, taking just 79 minutes to kick off his bid for a record-equalling seventh title.
The six-time champion, and record 16-time Grand Slam title winner, will face colourful Italian Fabio Fognini for a place in the last 32.
Federer, shunted out on to Court One for his 2012 opener, fired down nine aces in his straightforward win over left-hander Albert Ramos, the world number 43 who has never won a match on grass.
Federer, without a Grand Slam title since the 2010 Australian Open, is bidding to equal Pete Sampras's record of seven Wimbledon titles.
But he has fallen in the quarter-finals in the last two years, losing from two sets to love up for the first time in his career in 2011 when he went down to France's Jo-Wilfried Tsonga.
Djokovic and Federer then saw two dangerous rivals knocked out of their section of the draw.
Czech sixth seed Tomas Berdych, the 2010 runner-up, slumped to a 7-6 (7/5), 7-6 (7/4), 7-6 (7/4) to Latvia's Ernests Gulbis, the world number 87.
American 11th seed John Isner, who famously won the longest match in history at Wimbledon two years ago, went down 6-4, 6-7 (7/9), 3-6, 7-6 (9/7), 7-5 to Colombia's Alejandro Falla, the world 73.