Friday, 17 August 2012:

The resurgent Venus Williams has warned US Open champion Samantha Stosur she'll be up for the fight when the two clash in a heavyweight Cincinnati Masters quarter-final.

Stosur's return to a semblance of form continued with a 6-1 6-3 defeat of Russian Ekaterina Makarova but the third seed faces a sterner test next against Williams.

The American is through to her fourth quarter-final since emerging from a seven-month illness-enforced lay-off and they have all come at Premier events - in Miami, Charleston, Rome and now Cincinnati.

The seven-times grand slam champion and former world No.1 is fast gaining momentum and will no doubt be extra motivated to gain some sisterly revenge against Stosur.

It will be Stosur, not Serena Williams, who will arrive in New York next week aiming to defend her US Open title after the Australian upset the 14-times major winner in last year's dramatic decider at Flushing Meadows.

"Before all my injuries and illnesses, I was No.2 in the world and Serena was No.1 and we were No.1 in doubles," Venus said after crushing seventh seed Sara Errani 6-0 6-3 on Thursday.

"We were literally on top of the world until a lot of things came crashing down on us. I'd like to work my way back.

"Of course that's a dream for me. I dream of those things. That's why I'm here because I feel like I still have it.

"It's one match at a time, pretty much. I've beaten two seeds here now, players who are having exceptional years and are confident.

"For me to be in this tournament and getting wins over both of those players feels really good. I want to continue this in my next match tomorrow."

While Venus charged, Serena stumbled through to the last eight with a scratchy 6-4 6-3 defeat of Urszula Radwanska.

The Polish challenger, younger sister of top seed Agnieszka Radwanska, led Serena twice in the opening set but was unable to overpower the American.

"I was tired out there," confessed Williams, clearly fatigued after claiming a fifth Wimbledon title and the Olympic gold medal over the six weeks.

"I just told myself to try and move my feet a bit, get through this match and go get some rest.

"My main goal is to do well at the US Open. I need to make sure I'm fit and healthy for that."

Agnieszka Radwanska beat American Sloane Stephens 6-1 4-6 6-4 while fourth seed, and former Wimbledon winner, Petra Kvitova advanced 6-2 6-2 over China's Peng Shuai.

German fifth seed Angelique Kerber beat Czech Andrea Hlavackova 6-4 7-6 (7-5).

On the men's side, world No.1 Roger Federer ended the run of Australian teenager Bernard Tomic with a 6-2 6-4 victory.

As Federer chases a fifth trophy in Cincy, his Olympic final conqueror Andy Murray's title defence is over after falling 6-4 6-4 to French lucky loser Jeremy Chardy.

Murray's exit leaves the Scot short of hardcourt match time heading to New York for the Open starting on August 27.

Sixth seed Juan Martin del Potro had troubles with his left wrist, requiring taping on his arm in the worst moments of his 7-6 (7-2) 2-6 6-1 defeat of Serb Viktor Troicki.

American 10th seed Mardy Fish continued to perform well on his home cement courts, beating Czech Radek Stepanek 6-3 6-3 with seven aces and 23 winners in 90 minutes.

AAP