BEIJING, Oct. 3 (Xinhua) -- In a battle between the China Open's first two champions, world number one Serena Williams edged Russian Maria Kirilenko in a close two-setter for her 70th win of the season and also a place in the quarterfinals on Thursday.
Third seed Agnieszka Radwanska of Poland, however, earned a 6-0, 6-2 victory over Slovenia's Polona Hercog without having to raise her game much above the ordinary.
Kirilenko again proved no match for Williams, who prevailed in all seven previous meetings and defeated the Russian 6-2, 6-0 and 6-3, 6-1 in their two previous meetings this year.
But this time in Beijing, it was as close as it could be, with Kirilenko having big chances in both sets.
Neither player could break early in the match, with Kirilenko becoming the first to draw blood with a break at 4-all, serving for the first set at 5-4. She even had a 40-0 lead and triple set point. But Williams fought them all off and ended up winning the set on a Kirilenko double fault after 50 minutes of play.
Kirilenko went ahead again in the second set, breaking for 3-2 then consolidating it for 4-2, but Williams clawed her way back into it again, closing the match out in straights 7-5, 7-5.
"I just thought, 'What else can I do except fight for this point and the next point'," Williams said of triple set point in the first set.
"Maybe I got lucky a little bit. I just started to relax and kind of swing and not think about it too much out there. I'm obviously just really happy to get through this match today."
With the win, Williams braced her 70th win of the season. Her pervious personal best for a single season was 58 wins.
In quarterfinals Williams will play Caroline Wozniacki of Denmark, who dismissed American rising star Sloane Stephens 6-3, 6-1.
Radwanska used one hour and 20 minutes to send Hercog packing after converting on six out of her eight breaking points.
Coming up next for her will be German seventh seed Angelique Kerber, who defeated Italian Roberta Vinci 6-2, 6-4.
Earlier, eighth seed Jelena Jankovic got through in simple fashion, beating Carla Suarez Navarro 6-0, 6-0. The Serb will take on Lucie Safarova of the Czech Republic, who overcame German Andrea Petkovic 6-4, 6-7(4), 7-6(2).