BEIJING (AFP) - The Williams sisters and the Serbian duo of Jelena Jankovic and Novak Djokovic all blitzed their second-round Olympic opponents here on Tuesday. Jankovic, the women's world number one and Olympics top seed in the absence through injury of Ana Ivanovic, beat Ukraine's Alona Bondarenko 7-5, 6-1. The Serbian broke Bondarenko three times in the second set and put the match away with a lightning backhand pass down the line.But the 23-year-old from Belgrade, who was wearing a strapping on her troublesome right calf, did not look completely at ease around the court. Jankovic's compatriot Djokovic, seeded third in the men's draw, progressed confidently against Germany's Rainer Schuettler, 6-4, 6-2. The Williams sisters both earlier confirmed their status as among the hot favourites for gold in the women's singles, which has been hit by a raft of withdrawals. Fourth seed Serena took just 44 minutes to dispatch Australia's Samantha Stosur, the American eight-time Grand Slam champion breaking at 3-2 and taking complete control of the match to reel off the last 10 games to love. "It was clean," said Williams, who missed the 2004 Games in Athens through injury. "My way of improving on it is to keep it up."The 2000 doubles winner's round-three opponent is French 15th seed Alize Cornet, who subdued a vociferous home crowd in outclassing China's Peng Shuai 6-2, 6-2.Serena's sister Venus, the seventh seed, demolished Iveta Benesova of the Czech Republic, 6-1, 6-4. "I'm not sure that I faced any breakpoints today, so that's really good," said Venus, who has five Wimbledon titles among her seven Grand Slam crowns. "That's good for me going on in the later rounds, that I'm tough on my serve."I definitely feel more confident with every match that passes. That's what winning does."Russian sixth seed Dinara Safina stayed in the mix with a 7-6 (7/3), 6-1 win over Spaniard Maria Jose Martinez Sanchez, while Slovakian 16th seed Dominika Cibulkova cruised past Bulgaria's Tsvetana Pironkova 6-2, 6-2. But two other women's seeds were knocked out in morning play.Daniela Hantuchova of Slovakia, the 10th seed, lost to Danish teen Caroline Wozniacki 6-1, 6-3, while Polish eighth seed Agnieszka Radwanska went down 6-3, 7-6 (8/6) to Italian Francesca Schiavone. In the men's second round, French duo Gilles Simon, the 10th seed, and Gael Monfils saw off Guillermo Canas of Argentina and Romanian Victor Hanescu respectively. There was also a win for 17th-seeded Czech Tomas Berdych over Italy's Andreas Seppi, and a win for Belgian Olivier Rochus who was a set ahead of Janko Tipsarevic when the Serbian retired with an injury. Incoming men's number one Rafael Nadal will later face Australia's Lleyton Hewitt, who last occupied the top ranking in June 2003. Top seed Roger Federer has a mismatch against El Salvadoran invitee Rafael Arevalo, the world 447, while third-ranked Novak Djokovic is up against Wimbledon semi-finalist Rainer Schuettler. Eighth seed James Blake, the last remaining US men's player, faces injury-hit Slovakian Dominik Hrbaty.