Roger Federer is through to the quarter-finals of the Olympic men's singles tournament while Novak Djokovic also won.
Top two seeds in the men's tennis event reach the quarters
World number one Roger Federer is through to the quarter-finals of the Olympic men's singles tournament after seeing off Denis Istomin in straight sets at Wimbledon.
It was a tougher than expected match for the Wimbledon champion, who made the perfect start with a break of serve in his opponent's first game but allowed Istomin to level.
The Uzbek then had three break points at 5-5 but could not take them and he paid the price, with Federer wrapping up a 7-5 6-3 victory on Court One.
The Swiss star said: "It was tough. I started really well, I went into the lead 3-0 and he came back. I was a little bit shaken up I guess. He did well, he played aggressively, started to serve well, not to mention the rain delay.
"At 5-5 it wasn't very comfortable, I got a bit lucky obviously. Then I think I was able to play a bit more aggressively, I relaxed and then I played a good match in the end."
Djokovic relief
Second seed Novak Djokovic looked in even more trouble when he dropped the opening set to a rejuvenated Lleyton Hewitt, but the Serb dug in and eventually triumphed 4-6 7-5 6-1 in a high-quality match.
Hewitt, the champion at Wimbledon 10 years ago, has been dogged by injuries over the past few seasons and may have retired but for radical toe surgery earlier this year.
He needed a wild card to get into the tournament after dropping to 159th in the world but more than justified it with a two victories and a superb performance on this occasion.
Djokovic was a little below his best in the opening set, at times struggling to keep his feet on the dusty surface, but that was to take nothing away from Hewitt, who broke to lead 5-4 and then clinched the first set with a searing forehand winner.
Djokovic cut out the errors to pile the pressure on Hewitt and got his reward with a break for 5-3, letting out a huge roar, but the Aussie promptly broke straight back.
The 31-year-old could not hold on to force a tie-break, though, and in the decider Djokovic's weight of shot was just too much for Hewitt.
Things certainly do not get any easier for the second seed, who next faces a blockbuster quarter-final against fifth seed Tsonga.
The Frenchman recovered impressively from his titanic battle against Raonic to defeat Spain's Feliciano Lopez 7-6 (7/5) 6-4.
Eighth seed Juan Martin Del Potro also reached the last eight despite dropping a set to 12th seed Gilles Simon, the Argentinian prevailing 6-1 4-6 6-3, while 11th seed Nicolas Almagro from Spain beat Steve Darcis 7-5 6-3.
He will play Japan's Kei Nishikori who pulled off a late-night shock as he defeated fourth seed and Wimbledon quarter-finalist David Ferrer of Spain 6-0 3-6 6-4.
Nishikori led 5-4 on serve in the third set when the decision was taken to move the match under the roof on Centre Court, and the 15th seed won four of the five points played to secure arguably the best result of his career.
Williams wins
In the women's event, Wimbledon champion Serena Williams cemented her status as the favourite for gold with a crushing 6-1 6-0 victory over Russia's Vera Zvonareva to reach the last eight.
The American, seeded fourth, needed only 51 minutes to cruise through under the Centre Court roof against the bronze medallist from Beijing four years ago.
Williams already has two gold medals to her name in women's doubles with sister Venus, and were she to match that in singles, she would join Steffi Graf in winning all four grand slam titles and the Olympics in her career.
Williams gave much of the credit to the Centre Court roof, saying: "This is like a dream court. Grass is a dream court, but then to play indoors on grass... oh my God it's crazy."
She will next face eighth seed Caroline Wozniacki, who was cheered on by the Danish handball team in a 6-4 6-2 victory over Daniela Hantuchova.
Kim Clijsters kept alive her hopes of a medal at her first and last Olympics by defeating 11th seed Ana Ivanovic of Serbia 6-3 6-4 on a packed Court 18.
The Belgian crowd favourite will retire for the second time after the US Open later this month but for the moment she seems to have put her injury troubles behind her.
Clijsters, who will now face Maria Sharapova, feels she is coming into peak form just at the right time.
The Belgian said: "At this stage of the tournament, you have to fight and you have to play some of your best tennis, and I did. I felt like I was doing a lot of good things out there today, and I served a little bit better at the important points."
Sharapova gained revenge for her Wimbledon fourth-round exit as she defeated Germany's Sabine Lisicki in a tight tussle.
The match looked set to go the same way when Lisicki edged a nip-and-tuck tie-break and then went a break up in the second set, but Sharapova showed her trademark battling qualities to turn things around and come through 6-7 (8/10) 6-4 6-3 after two hours and 47 minutes.
The Russian said: "I was really happy I was able to beat her today. Obviously losing to her a few weeks ago, I was not really happy with the way that I played, so I wanted to change that result.
World number one Victoria Azarenka was given a real test by Russia's Nadia Petrova but she fought back from a break down in the second set to win 7-6 (8/6) 6-4.
Maria Kirilenko's quarter-final opponent will be last year's Wimbledon champion, Czech Petra Kvitova, who was in superb form on Wednesday as she crushed Italy's Flavia Pennetta 6-3 6-0.
If Venus Williams is to win a record fourth Olympic gold medal it will have to be in doubles after she was beaten by seventh seed Angelique Kerber in a very close match.
The American, who won the singles title in Sydney 12 years ago, is battling Sjogren's Syndrome but has found some impressive form on Wimbledon's grass and was edged out 7-6 (7/5) 7-6 (7/5).
German Kerber reached the semi-finals at Wimbledon but she will have to beat top seed Azarenka if she is to do the same here.
Doubles
Meanwhile, more records were broken in the men's doubles clash between Marcelo Melo and Bruno Soares and Tomas Berdych and Radek Stepanek, which the Brazilians eventually won 1-6 6-4 24-22.
It was 18-18 when the doubles match was called off because of bad light, and they were only three games short of equalling Tsonga and Raonic when Melo and Soares clinched victory.
It was, though, the most games ever played in a set and in a match in Olympic doubles history.
