Venus Williams was one service game from holding up her end of a projected sisters semifinal at the Australian Open, until she stumbled in a flurry of errors and lost to No. 16 Li Na.
Li reached the Grand Slam semifinals for the first time with the 2-6, 7-6 (4), 7-5 quarterfinal win today, giving China two players into the last four of a tennis major for the first time.
"Best day of my whole life," Li said, grinning widely.
Zheng Jie was playing a semifinal against former No. 1-ranked Justine Henin in the other half of the draw.
The experts expected Venus Williams to beat Li and set up a semifinal with her sister and defending champion Serena Williams, who was playing her quarterfinal in the following match at Rod Laver Arena.
And when the seven-time major winner was serving for the match at 5-4 in the second, it seemed a formality.
But Li rallied, breaking Williams and eventually forcing and then dominating a tiebreaker against the former No. 1-ranked American.
Williams held to open the third set, which then featured six consecutive service breaks until Li held to even it at 4-4. She broke Williams and then had her own chance to serve for the match, but she didn't win a point in that game.
Williams returned the favor, losing four consecutive points on her serve to give Li a second chance to serve it out at 6-5.
The match featured a combined 110 unforced errors, Williams committing 53 of those. Williams had 11 double-faults - five in the third set - against Li's five in the match.
Rafael Nadal, who won last year's final in five sets over Roger Federer, withdrew because of an injured knee while trailing Britain's Andy Murray 6-3, 7-6 (2), 3-0 in Tuesday's quarterfinals.
Andy Roddick also needed a medical timeout - after the first set of his match against No. 14 Marin Cilic. His sore right shoulder was making his fingers numb.
Roddick played on for another four sets. But Cilic advanced 7-6 (4), 6-3, 3-6, 2-6, 6-3.
Federer will play Nikolay Davydenko in the quarterfinals today. Novak Djokovic and Jo-Wilfried Tsonga meet in a rematch of the 2008 final.