Serena Williams powered past Severine Bremond in the fourth round
Serena Williams will take on her sister Venus in the quarter-finals of the US Open after both enjoyed comfortable fourth-round wins on Monday.
Venus, seeded seven, thumped Agnieszka Radwanska of Poland 6-1 6-3, before fellow two-time champion Serena beat France's Severine Bremond 6-2 6-2.
The sisters will play for the 17th time, with Venus's recent win in the Wimbledon final making the score 8-8.
Dinara Safina and Flavia Pennetta will also meet after victories on Monday.
"It's so soon," fourth seed Serena said of playing her sister in the last eight. "You know, it's just disappointing to be so soon.
"Even the semis would have been better than the quarter-finals, but at least one of us will make it to the semis,.
Slowly I started to feel like I still can push myself. I am really happy that I won
"I've got probably the toughest match of the tournament coming up next, so I've got to be ready."
Venus said: "It's tough to play her because she's so good. We're going stronger than ever, in my opinion."
Russia's Safina continued her impressive run of form by sweeping past Germany's Anna-Lena Groenefeld 7-5 6-0 and into the quarter-finals.
The sixth seed was given a stern test by Groenefeld before edging the first set but saw her opponent collapse completely in the second.
Safina, 22, completed her 18th win in her last 19 matches, but admitted afterwards her coach Zeljko Krajan had to persuade her to play the match.
"After the warm-up I just started to cry. I could not stop crying," Safina said. "My coach said, 'Just go out there'.
"I said, 'I cannot push anymore myself'. He said, 'We know that you're not a machine. Just go out there and don't think.'
"He told me again, 'Just please don't show me any emotions, like these negative emotions. If you want, don't show even positive. Just go on the court and do whatever you can on this day.'
"Slowly I started to feel like I still can push myself. I am really happy that I won."
Safina will face Pennetta next after the Italian thrashed former world number one Amelie Mauresmo 6-3 6-0.
Mauresmo had a nightmare, producing 14 double faults and 40 unforced errors on her way to a crushing defeat.
The 32nd seed's serve was poor from the start and she fell apart after being broken at 3-3 in the first set.
Pennetta expects a tough test from French Open runner-up and Olympic silver medallist Safina.
"She is in good shape," said the Italian. "So I will have to serve well. My first serve is going to be important and also the return.
"For sure, I will have to play my best tennis to beat her."