London: Five-time Wimbledon champion Venus Williams suffered her worst All England Club defeat in 15 years on Monday, but top seeds Novak Djokovic and Maria Sharapova and Roger Federer 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 feel like I am a great player who has had to deal with exceptional circumstances. I don't have time to feel negative. It doesn't feel good. I am as tough as nails, I don't have time to be sorry for myself."
The American star arrived at Wimbledon, where she was unseeded for the first time since her 1997 debut, short of confidence having been sidelined with Sjogern's Syndrome, a disease which causes joint pain and fatigue.
Monday's defeat was just her 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 face Polish third seed Agnieszka Radwanska for a place in the last 32.
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 either America's Ryan Harrison or Lu Yen-Hsun of Taiwan.
"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. The grass was untouched. It was so soft, so smooth. It was great to play on."
Third seed Roger 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 Ramos, the world number 43 who has never won a match on grass.
"The crowd were excited to see us play. I played a good match against a guy who doesn't have much experience on grass courts," said the Swiss.
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.
Sharapova, who completed a career Grand Slam with victory at the French Open, was second-up on Centre Court and 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, in the last 64.
"It's always difficult when you have had no matches on grass before Wimbledon," said Sharapova. "It can be tricky but you just focus on what you have to do."
US Open champion Samantha Stosur and ex-French Open winner Li Na also reached the second round.
Stosur, the fifth-seeded Australian, had the honour of being the first woman into the last 64, cruising past Spain's 40th-ranked Carla Suarez Navarro 6-1, 6-3.
Her win earned her a second round match with Arantxa Rus of the Netherlands.
Chinese 11th seed Li Na, the 2011 French Open winner, enjoyed an emphatic 6-3, 6-1 victory over Ksenia Pervak of Kazakhstan. Li next faces Romania's Sorana Cirstea.
Radwanska, a quarter-finalist in 2008 and 2009, made the second round with a 6-3, 6-3 win over Slovakia's Magdalena Rybarikova.
Kim Clijsters, in her last Wimbledon by all means, too sped through to the second round with a 6-2, 6-4 victory over Jelena Jankovic.
Czech sixth seed Tomas Berdych, the 2010 runner-up, was knocked out of Wimbledon on Monday, losing 7-6 (7/5), 7-6 (7/4), 7-6 (7/4) to Latvia's Ernest Gulbis.
World 87 Gulbis will tackle either Italy's Simone Bolelli or Jerzy Janowicz of Poland for a place in the last 32.