Five-time champion Venus eased to a 6-1, 6-2 victory over Poland's Agnieszka Radwanska while Serena, a two-time champion, saw off Belarusian eighth seed Victoria Azarenka 6-2, 6-3.

The sisters have made 12 Wimbledon finals appearances and there were few signs today that the family monopoly is about to be broken.

Venus, 29, who will be in her eighth Wimbledon semi-final in 10 years, next tackles Dinara Safina, the world number one and top seed, who will be playing in her first.

Serena, the second seed, will face Russian fourth seed Elena Dementieva.

Venus, bidding to become the first woman to win a hat-trick of Wimbledon titles since Steffi Graf's treble from 1991 to 1993, has now won 32 consecutive sets at the All England Club, a run stretching back to the third round in 2007.

She shrugged off the heat to breeze through the first set in 27 minutes, serving up two love games on her way to a 5-0 lead before the 11th seeded Radwanska got on the board.

The Pole broke to love to lead 2-0 in the second set but that was as good as it got for the 20-year-old who had no answer to the American's brutal hitting power. Venus ran away with the next six games to claim victory in 68 minutes.

"I really had to play well. It was close at the start of the second set. She's a good grass court player so I'm happy just to get through," said the third seed.

"If it was an all-Williams final that would be fantastic but we still have great players to meet and will have to bring our best tennis to the court."

Safina, still searching for a first Grand Slam title, had to come back from a set down for the second day in succession as the Russian saw off unseeded German teenager Sabine Lisicki 6-7 (5/7), 6-4, 6-1.

Safina was hit with a code violation for racquet abuse when she double-faulted on set-point in the first set tie-break, but she recovered her composure to make the last four.

"I think I was Santa Claus today serving so many double faults," said Safina, who served up 15 in all.

"It's not going to be easy playing against Venus. She likes playing on grass and I have nothing to lose."

"Grass is definitely her best surface. She loves playing here in Wimbledon. I will go out and play the way I can play.

I played her in Rome and I beat her in Rome."