July 3 (Bloomberg) -- Defending champion Venus Williams and her sister Serena both won today in straight sets to set up their third showdown in the Wimbledon tennis final.

The 28-year-old Venus beat Russia's Elena Dementieva 6-1, 7-6 (7-3) on Centre Court at London's All England Tennis Club. Then Serena, 26, defeated Zheng Jie of China 6-2, 7-6 (7-5) in a rain-affected match.

``I'm just happy to be back in a Grand Slam final, I love it,'' Serena Williams told the BBC. She said Venus will ``be the toughest person I've played. I'm excited.''

Venus Williams, the seventh seed, is trying to become the first woman to successfully defend the title at the only grass- court Grand Slam event since Serena beat her in the 2002 and 2003 finals.

Serena, the No. 6 seed and an eight-time Grand Slam winner, stops Zheng from becoming the first woman from China to make it to the singles final in one of the four majors.

Germany's Rainer Schuettler beat Arnaud Clement of France 6-3, 5-7, 7-6 (8-6), 6-7 (7-9), 8-6 to reach the men's semifinals, where he'll play Spain's Rafael Nadal tomorrow. Five-time defending champion Roger Federer faces Marat Safin in the other match.

Venus Williams, who has won Wimbledon four times and the U.S. Open twice, hasn't dropped a set in the tournament. She broke in the first game of the match against Dementieva, a Russian who was the highest seed left in the draw at No. 5 and seeking her first final berth at the All England Club.

Break Points

Williams saved four break points in the next game, then broke Dementieva again and held for 4-0. She broke the Russian at love to wrap up the first set.

Williams saved a break point in the first game of the second set, then got an early break. Dementieva, a runner-up at the French and U.S. Opens in 2004, broke back immediately when the ball struck the top of the net and fell just over.

The remainder of the set went with service to force a tie- break. Dementieva took a 3-2 lead when Williams returned into the net, before the American took the final five points.

``She started really well,'' Dementieva told reporters. ``In the beginning of the match she really dominated, put a lot of pressure on my serve. She was serving unbelievably well, so it was really hard just to make her play.''

Rain Delays

Serena Williams started with a break in her match against Zheng, who only gained entry to the tournament as a wildcard. There was another break in the fifth game and Williams had four set points in the seventh, which Zheng saved.

Williams held to love when they returned after the first of two rain delays to take the set.

Zheng then broke for a first time in game six of the second set, though Williams replied in the next game. The Chinese player led 40-30 on serve in game 11 when rain forced them to leave the court again -- this time for around one hour and 20 minutes.

She faced two break points but held, while Williams also defended a break to take the set into a tie-break. Williams led 5-2 after two straight aces, but Zheng fought back to level at 5-5. Zheng lost on a double fault when facing match point.

``She definitely pushed me,'' Serena Williams said. ``She played a great game. She played like she had nothing to lose, which she didn't.''

Schuettler, at 32 the oldest player remaining in the men's tournament, finally overcame Clement in a match lasting more than five hours. He is the first German man in the semifinals since Michael Stich in 1997.

To contact the reporter on this story: James Cone in London at jcone@bloomberg.net.

Last Updated: July 3, 2008 14:18 EDT