Venus Williams lost two service games in an otherwise thoroughly convincing triumph over Paraguay's Rossana de los Rios as she began her Wimbledon campaign in determined mood.

Perhaps mindful of the fading light, Williams sped to a 5-0 lead after 15 minutes of the first set before recovering from a minor slump to claim it 6-3.

Williams also won the first five games of the second set before eventually ending the contest with a 6-2 success.

The second seed had faced a long wait for action on Court One thanks mainly to Nikolay Davydenko's five-set epic victory against Kevin Anderson, which preceded Andy Roddick's swift win over Rajeev Ram.

But her focus remained firmly intact as she began with an ace at 7.26pm before continuing to serve viciously during a first game in which her opponent failed to land a shot in the court.

Williams lost the next two points but recovered to break serve and won the next three games without dropping a point.

The five-times winner appeared in invincible form but her 34-year-old opponent put up a better fight in the sixth game, eventually getting off the mark with a pass shot that was greeted warmly by the crowd.

The Paraguayan continued to improve and earned break point after a long rally, before a backhand cross-court effort pulled the score back to 5-2.

De los Rios held serve again and her increasing confidence was evident when she lobbed Williams brilliantly, but the favourite soon clinched the set with an ace.

Williams quickly took command of the second set by breaking De los Rios, the third oldest competitor in the women's singles event.

And, although the games were generally closer than during the American's opening surge, Williams matched her start to the first set as her power and accuracy proved too much.

However, De los Rios refused to be whitewashed and a skilful drop shot earned her a second break of service. The Paraguayan held her own serve to ensure the match went beyond the hour mark before Williams finished the contest off in convincing fashion.

Justine Henin enjoyed a winning return to Wimbledon as her bid to complete a career Grand Slam got off to a strong start.

Henin, who spent 20 months in retirement before returning to the professional circuit in January, rewarded the patience of the spectators out on Court 12 as she eased aside Latvian youngster Anastasija Sevastova 6-4 6-3.

Wimbledon remains the only major title missing from Henin's trophy cabinet in a career that has brought her four French Open crowns, two US Open triumphs and an Australian Open victory, and her desire to set that right was a key motivating factor in her decision to return to the sport.

And just hours after fellow Belgian Kim Clijsters had triumphed on her SW19 comeback following two years in retirement, Henin produced a workmanlike display to ensure she would also be present in round two.

The 28-year-old Henin arrived at the All England Club in good touch having triumphed at the grass-court Unicef Open in Holland at the weekend to clinch her second title since coming out of retirement.

But the 17th seed was forced to dig deep in a competitive opening set against world number 57 Sevastova, who also suffered a first-round exit in her only previous outing at SW19 12 months ago.

All appeared to be going to plan when Henin broke the Sevastova serve in third game, but the Latvian stunned her more experienced opponent by breaking back immediately as Henin fired tamely into the net.

Sevastova held to love in the seventh game to underline the threat she posed, but with the score at 4-4 Henin's class began to tell.

A poor service game saw Sevastova slip to 0-40 on a wild and wide forehand, and Henin punished her opponent with a devastating return winner to take the key break before holding in the next to seal the opening set.

With the second set going with serve to 3-3, Henin turned the screw on Sevastova in the seventh game, forcing her onto the back foot before earning a break-point chance.

A firm forehand return forced a mis-hit from Sevastova, who skied the ball to present Henin with an easy smash to take the break and the initiative in the set.

A trademark one-handed backhand winner was the standout shot of the next game as Henin held to love, and another break in the next did for Sevastova, after 59 minutes on court.

French Open champion Francesca Schiavone could not maintain the form which brought her Roland Garros glory as she made a swift Wimbledon exit.

The Italian, who turns 30 on Wednesday, was a shock winner of the Paris title earlier this month when she defeated another surprise finalist, Australian Sam Stosur.

That maiden grand slam victory of her career nudged her up the rankings, elevated her profile, and resulted in her being made fifth seed for Wimbledon.

But she was on the end of a major first-round upset as Russian Vera Dushevina battled back from dropping the first set to win 6-7 (0/7) 7-5 6-1 on Court Two.

Kim Clijsters made the perfect start to her Wimbledon comeback today as she posted a straight-sets victory over Maria Elena Camerin to book a place in round two.

After ending two years in retirement last summer, Clijsters' SW19 return kicked off with an assured 6-0 6-3 triumph over her unseeded Italian opponent.

The eighth-seeded Clijsters' last appearance at Wimbledon came with a semi-final defeat against Justine Henin in 2006, and her fellow Belgian - herself also returning to the All England Club this year after ending a spell in retirement - awaits her in round four should both successfully negotiate the coming days.

Next up for Clijsters is a second-round clash with world number 104 Karolina Sprem of Croatia, who defeated the United States' Bethanie Mattek-Sands 6-3 6-4 in the first match on Court 16.

Nadia Petrova, the 12th seed from Russia, also progressed with a 6-4 6-3 win over Tatjana Malek of Germany, while her compatriot Vera Zvonareva, seeded 21, defeated Spain's Nuria Llagostera Vives 6-4 6-1.

Maria Kirilenko further bolstered the Russian contingent in round two as the 27th seed rallied from a set down to see off Switzerland's Stefanie Voegele 2-6 6-4 7-5, while 30th-seeded Yaroslava Shedova of Kazakhstan was a 6-1 6-4 winner over Slovenia's Polona Hercog.

Yung-Jan Chan of Chinese Taipei ousted Switzerland's Patty Schnyder 6-0 6-2, Alla Kudryavtseva of Russia beat Sofia Arvidsson of Sweden 6-4 6-1, Shenay Perry of the USA defeated Anastasiya Yakimova of Belarus 6-2 4-6 9-7 and Andrea Hlavackova of the Czech Republic was a 6-3 6-2 victor over Noppawan Lertcheewakarn of Thailand.

The 16-year-old former Wimbledon junior champion Laura Robson was another opening day casualty.

Robson had pledged to build on her encouraging three-set defeat by Daniela Hantuchova on her Wimbledon debut 12 months ago, and she duly obliged in a 6-3 7-6 (7/5) loss to fourth seed Jelena Jankovic in which she saved four match points.