MELBOURNE, Australia -- Sloane Stephens sat for nine minutes, mostly staring at the court and trying to forget the curious timing of Victoria Azarenka's medical timeout.

She may have been the only one trying to ignore it.

The 19-year-old American had just saved five match points and broken Azarenka. But she knew she had to hold serve to stay in her first Grand Slam semifinal whenever Azarenka -- the No. 1 player and defending Australian Open champion -- returned to Rod Laver Arena.

The restless murmuring in the crowd gave way to slow claps. Why had Azarenka chosen that very moment for a medical break?

Azarenka eventually hustled onto the court, and Stephens won only three more points.

"I almost did the choke of the year," Azarenka said in a frank admission during an on-court interview. "At 5-3, having so many chances, I couldn't close it out."

The crowd that had cheered wildly for Stephens, only 25 hours after she ousted an injured Serena Williams, gave Azarenka tepid applause as she left the court. She'll face 2011 finalist Li Na.

Azarenka's immediate postmatch remarks suggest she panicked after failing to convert five match points. She had little trouble finishing the match after she came back, and the No. 29-seeded Stephens had cooled off.

"I just felt a little bit overwhelmed. I realized I'm one step away from the final and nerves got into me for sure," Azarenka said.

Medical staff said Azarenka had timeouts for treatment of left knee and rib injuries. The rib needed to be manipulated because it was affecting her breathing. Tournament director Craig Tiley said Azarenka hadn't broken any rules.

key matches

Men's semifinals
No. 1 Novak Djokovic def. No. 4 David Ferrer 6-2, 6-2, 6-1.
Women's final
Midnight
No. 1 Victoria Azarenka vs. No. 6 Li Na