MIAMI, FL, USA - Serena Williams did her part to set up a family clash at the Sony Ericsson Open on Wednesday afternoon, edging China's Li Na in a tight three-setter in the quarterfinals, 46 76(1) 62.

Serena, ranked and seeded No.1 and a five-time winner at the $4.5-million event, had her hands full from the get-go against Li, who won the first five games of the match - eventually closing out the first set, 6-4, and threatening a number of times to break serve in the second set. But Serena held on every time, saving six break points in total, then raced through the tie-break and the third set to move into the semis of the prestigious Sony Ericsson WTA Tour stop.

"I'm glad to have gotten through," Serena said. "I've played a lot of Chinese girls this week, wow. It was definitely a new experience. And hey, it's obviously good for the Chinese Fed Cup team. They're all obviously really consistent. They hit a flat ball and keep it low. They're good players, as everyone is on the Tour."

Li had given Serena problems in the past, pushing her to three sets in their first meeting at the Australian Open in 2006 then actually beating her in their second meeting, in the early rounds of Stuttgart last fall, when she was also ranked No.1.

"Both Williams sisters can win any tournament," Li said. "They're so strong mentally and they're so strong on the court. They put so much pressure on you."

Serena has now singlehandedly bounced China's Top 3 from the Sony Ericsson Open, having beaten Peng Shuai in the third round and Zheng Jie in the fourth round. Zheng also came very close to upsetting the world No.1, leading 2-0 in the third set before ultimately falling, 75 57 63, in a very entertaining nail-biter.

Venus Williams, seeded No.5 and a three-time winner in Miami, took on No.26 seed Iveta Benesova in the last quarterfinal match under the lights. Although the middle of the match was certainly no cakewalk for Venus - she lost four of five games in one stretch to go down 4-1 in the second set - it was mostly smooth sailing for the powerful American, who seemed largely untroubled by her lefty opponent during a 61 64 win. She has never lost a set to Benesova.

"Sometimes when things aren't going your way, the games start going so fast because everyone out there is good," Venus said. "Fortunately it wasn't a double break. That may have been a little tougher to come back from. I look at it as one break - I don't look at it as the score is 1-4."

The Williams sisters have played 19 times before, with Venus leading the series, 10-9. Venus has also won their last two meetings and five of their last seven, perhaps indicating she's on somewhat of a roll against her little sister. But some added incentive for Serena is that if she loses the match, she also loses her No.1 ranking - not to Venus, but to current world No.2 Dinara Safina.

Svetlana Kuznetsova and Victoria Azarenka, who won their quarterfinals on Tuesday, will play the first semifinal at 1 p.m. local time on Thursday; the Williams sisters will clash at night, not before 9 p.m. local time (after the men's match).