MELBOURNE, Australia -- Three times in the first four sets, David Ferrer faced the prospect of being ousted of the Australian Open by a fellow Spaniard who had never beaten him in a dozen competitive matches.
The No. 4-seeded Ferrer survived once in the third set and twice in the fourth when No. 10 Nicolas Almagro was serving for the match, but he held firm and finally advanced to his fourth semifinal in six Grand Slam events with a 4-6, 4-6, 7-5, 7-6 (4), 6-2 win on Tuesday (Australia time).
"It was (a) miracle I won this match, I think," Ferrer said. "I tried to fight every point, that's my game. I always try to fight."
Almagro dominated the first two sets and was serving for the match in the third when Ferrer bounced back, breaking in the crucial 10th game and then breaking his Davis Cup teammate again.
Ferrer will next play either Novak Djokovic, who is bidding for a third consecutive Australian title -- unprecedented in the Open era -- or No. 5 Tomas Berdych. Ferrer has played four semifinals in Grand Slams and lost them all.
Li Na had an easier time as the first woman moving to the semifinals.
The sixth-seeded Li advanced to her third Australian Open semifinals in four years with a 7-5, 6-3 win over Agnieszka Radwanska, which ended the Polish player's 13-match winning streak.
"She's a tough player. I was feeling today against a wall," said Li, who lost the 2011 Australian Open final to Kim Clijsters only months before her Grand Slam breakthrough at the French Open.
"She can hit everywhere, but without a mistake. I was feeling just very tough. You have to focus on every shot. Not every point, every shot."
Li will play Maria Sharapova, the 6-2, 6-2 winner of Tuesday's all-Russian quarterfinal against Ekaterina Makarova.
The quarterfinals on the other half of the draw will feature American teenager Sloane Stephens against Serena Williams, who is aiming for a third consecutive major title, and defending champion Victoria Azarenka against two-time major winner Svetlana Kuznetsova.
Stephens has heard a lot of advice from Serena Williams. Pointers on her groundstrokes, and even on her grunts.
It has been mostly gentle encouragement, occasionally spiced with headline-making comments from Williams, who has predicted the 19-year-old American will one day top the women's rankings.
As Stephens learned earlier this month, though, it's one thing to play with Williams, another to play against the 15-time Grand Slam champion.
With a comeback 6-1, 3-6, 7-5 win over Bojana Jovanovski on Monday, Stephens qualified for her first quarterfinal at a major tournament. Williams has already played at that level 34 times.
"It will be tough, obviously. It's quarters of a Grand Slam," Stephens said. "There won't be that, like, first time, 'Oh, my God, I'm playing Serena.' That's kind of out of the window now. So that's good."
Williams and defending champion Azarenka advanced Monday, losing just four games between them against Russian rivals. Williams beat No. 14 Maria Kirilenko 6-2, 6-0, and Azarenka defeated Elena Vesnina 6-1, 6-1.
On the men's side, No. 2 Roger Federer and U.S. Open champion Andy Murray stayed on course for a semifinal in their half of the draw.
Federer won 6-4, 7-6 (4), 6-2 over big-serving Canadian Milos Raonic, advancing to the quarterfinals at a Grand Slam for the 35th consecutive time, while Murray took advantage of Gilles Simon's fatigue for a 6-3, 6-1, 6-3 victory.
Federer will face 2008 Australian finalist Jo-Wilfried Tsonga, who beat friend and fellow Frenchman Richard Gasquet 6-4, 3-6, 6-3, 6-2.