US Open, Flushing Meadows
Dates: 30 August - 12 September Start time: 1600 BST
Coverage: Live text commentary on BBC Sport website and mobiles; updates on BBC Radio 5 live; live on Sky Sports
Clijsters sends out a message to her rivals with an imperious display
Defending champion Kim Clijsters demolished Ana Ivanovic 6-2 6-1 to ease into the US Open quarter-finals.
The pair struggled on serve until the Belgian broke twice to lead 5-2 and it proved to be the turning point as the Serb, 22, capitulated.
After taking the first set, the second seed raced to a 4-0 lead and soon wrapped up the victory in 59 minutes.
Venus Williams was given a scare in the first set by Israeli 16th seed Shahar Peer before winning 7-6 (7-3) 6-3.
The American made just 48% of her first serves and was broken three times, and the two-time champion admitted afterwards she was still finding her way back after a recent knee injury.
"It was a little tricky - it was important for me to stay positive," said the 30-year-old third seed. On her fitness, she added: "I'm OK. It helps me not playing the doubles. I'm happy to be here and playing well."
I was on the big stage again. Lots of emotions came back, and I just felt a little slow and just a little bit out of it
Williams will next play French Open champion Francesca Schiavone, who comfortably saw off 20th seed Anastasia Pavlyuchenkova with a 6-3 6-0 win.
The Italian sixth seed continued her fine run with a strong performance on Louis Armstrong Stadium to overcome the 19-year-old Russian, who was playing in the fourth round at a Grand Slam for the first time.
Pavlyuchenkova required medical attention on her right arm and racked up four double-faults and 29 unforced errors as Schiavone made the last eight in New York for the first time in seven years.
With blustery conditions returning to Flushing Meadows on Sunday, Clijsters produced a display that showed all the signs of a player determined to keep hold of the crown she won in 2005 and 2009.
The Belgian and Ivanovic suffered early breaks of serve, but it was the defending champion who slowly seized control with a dominant combination of aggression and tireless defence.
It took Clijsters, who returned to the sport last year after retiring in 2007, half an hour to wrap up the opening set with a crushing backhand that left Ivanovic stranded and increasingly frustrated.
Although Ivanovic, currently ranked 40, showed brief glimpses of the talent that took her to number one status two years ago, there was no stopping Clijsters as she powered to a 4-0 lead before sealing another victory without dropping a set.
After taking her match-winning run at the US Open to 18 to set up a clash with fifth seed Samantha Stosur, she said: "I played well and I'm happy to get through in two sets.
"It's all about staying with her. She's a player who likes to grow in confidence and then she takes more risks when she's ahead. Once she started to make errors I tried to really get in and be aggressive and play my game. I'm happy with the way I'm improving."
Ivanovic admitted: "I was on the big stage again. Lots of emotions came back, and I just felt a little slow and just a little bit out of it."
Australian Stosur, who has never previously been further than the second round of the tournament, took the first set in a promising start against 12th seed Elena Dementieva.
But her groundstrokes became increasingly erratic as she failed to win a service game in the second set.
It appeared that she was bound for defeat when her Russian opponent broke at the first opportunity in an astonishing final set that neither player seemed to have the nerve to close out.
Stosur was behind for much of the decider, saving four match points as she clung on at 5-2 down, but, after squandering a chance of her at 6-5 up, the pressure finally told on Dementieva in the tie-break.
The 6-3 2-6 7-6 (7-2) win took two hours 38 minutes, finishing after 0130 local time, and was Stosur's first hardcourt success over Dementieva in five meetings on the surface.