Venus Williams was in ruthless mode as she ended the challenge of fifth seed Ana Ivanovic in the US Open last 16.
Ivanovic had three chances to break Williams in her opening service game but could not convert them.
Twelfth seed Williams then broke the Serb with her first opportunity and wrapped up the first set.
The match had been eagerly anticipated but proved a damp squib as Williams broke at the start of the second set and again at 3-1 for a 6-4 6-2 win.
In the quarter-finals, the 27-year-old will face Jelena Jankovic, who shook off a second-set lapse and an early break in the third to roar past Sybille Bammer 6-4 4-6 6-1.
She arrived in time to practice at 1pm local time but did not start her match until about 9pm.
"Being here all day, I was quite exhausted - I had to drink coffee before the match to stay awake," she said.
Venus could face sister Serena in the semi-finals in what would be their first meeting since 2005 at Flushing Meadows.
"That would be awesome because it would mean that there is a Williams in the final, and it would mean that Americans have a chance to win," said Venus.
Serena Williams will face Justine Henin in the quarter-finals of a Grand Slam for the third time this year after both won their fourth-round matches.
"I'm still not where I want to be or near but I feel like I'm doing better "
Serena produced her most convincing display so far at this year's tournament to beat 10th seed Marion Bartoli 6-3 6-4.
The eighth seed, who has twice won the title at Flushing Meadows, began slowly, dropping her opening serve.
But she worked her way into the match against the Wimbledon runner-up and broke twice to take the opening set.
Another break at 2-2 in the second was enough to ensure victory.
World number one Henin crushed Russia's Dinara Safina 6-0 6-2 in the first match of the night session in New York.
The top seed was in superb form, hitting 13 winners, but Safina appeared overawed from the start and committed 23 unforced errors.
Safina did not manage to hold serve once as she capitulated in 59 minutes.
Henin and Williams met in the quarter-finals of the French Open and Wimbledon, the Belgian winning both.
Williams struggled in her opening three rounds in New York but looked in much better shape against Bartoli.
606: DEBATE
"Each match I feel like that I've got better," said Williams.
"I'm still not where I want to be or near. But I feel like I'm doing better, which is important."
Bartoli said that Williams' serve had been the main difference between the players.
"I think from the baseline I was fine, I was hitting the ball pretty well," said the French player.
"Even at 30-30 at 5-4 in the second set she served two aces. That's it, it's finished. When you play against somebody who serves like this, it's really hard to win the match."
~RS~q~RS~~RS~z~RS~37~RS~)