Williams is bidding to reach her seventh final at the All England Club

Defending champion Venus Williams produced a convincing display to overwhelm Maria Jose Martinez Sanchez and reach round four of Wimbledon.

The four-time champion powered her way through the first set in just 25 minutes and broke at 5-5 in the second to wrap up a 6-1 7-5 victory.

Williams now faces 18-year-old Russian Alisa Kleybanova and is joined in the last 16 by Elena Dementieva.

Fifth-seed Dementieva 7-6 (7-2) 7-5 will play Israel's Shahar Peer.

Peer, seeded 22, emerged triumphant after three hours and 25 minutes against ninth seed Dinara Safina.

French Open runner-up Safina was broken at 5-6 to concede the first set but, after saving match point at 4-5 down, snatched the second on a tie-break.

Suffering from a thigh injury that required extensive treatment, the Russian repeatedly lost her temper and was forced to save a second set point at 5-6 before double faulting to hand Peer a 7-5 6-7 (4-7) 8-6 victory.

Dementieva struggled to find any sort of consistency early on against Argentina's Gisela Dulko, who had benefited from walkover against the injured Lindsay Davenport in round two.

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Dementieva, a quarter-finalist in 2006, fought back to 3-4 by breaking in the sixth game and brought the match level at 5-5 when Dulko was wide with a forehand pass.

After the world number five stormed through the tie-break, the second set went with serve until, at 5-5, Dementieva broke and then served out to progress.

Williams, meanwhile, will be confident of reaching her seventh final at the All England Club after her impressive third-round win.

Having ill-advisedly attempted to take Williams on from the baseline in a completely one-sided first set, world number 101 Sanchez opted to regularly come to the net in the second.

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But Williams, seeded seven, was in commanding form and broke at 5-5 before serving out the match with a pair of booming aces, the second clocking 127 mph.

I was very pleased with the performance," the American told BBC Sport. "Things got close in the second set.

"She was really playing well and I had to come up with something more than she was giving."

"I was impressed with the way she changed strategy and made it really competitive in the second."

Williams plays Kleybanova after World number 42 overcame Japan's former world number one Ai Sugiyama 6-4 6-4.

Number two seed Jelena Jankovic, who beat Caroline Wozniacki in three sets, will face Tamarine Tanasugarn for a place in the last eight after the unseeded Thai beat Marina Erakovic 4-6 6-4 6-4.

Belarussian 16th seed Victoria Azarenka was ousted after a tough match against 21st seed Nadia Petrova, with the Russian winning 7-6 (13-11) 7-6 (7-4).

She now faces another Russian, Alla Kudryavtseva, Maria Sharapova's conqueror in round two, after she beat Shuai Peng of China 6-3 1-6 6-4.