The number four seed came back from two sets down against Nicolas Almagro and 5-4 in the third to take a dramatic victory at the Rod Laver Arena.
Australian Open: Ferrer battles back from the brink to book semi-final slot in Melbourne
David Ferrer stared defeat in the face three times before staging a dramatic comeback from two sets down to beat Nicolas Almagro and book his semi-finals berth at the Australian Open.
The fourth seed looked to be heading for the exit when, having been dominated by some brilliant play from the 10th seed for the first two sets, he faced Almagro serving for the match at 5-4 in the third.
But the Spaniard hustled along the baseline to claw his way back into the contest and take the third set on Rod Laver Arena.
Twice more Almagro had chances to serve out for victory but blew them both and Ferrer, who had won all 12 of their previous meetings, emerged a 4-6 4-6 7-5 7-6 6-2 winner after three hours and 44 minutes on Rod Laver Arena.
"It was a miracle I won this match," said Ferrer, who will face Novak Djokovic or Tomas Berdych in the last four.
"I tried to fight and do my best (but) next round ... I need to play my best tennis, better than today. Now I will need to rest but I have a day and a half."
Almagro contributed to his own downfall by stuttering when he had victory within his sights and his body let him down in the last two sets when he was hindered by a leg injury.
"I think I played my best tennis today but it wasn't good enough to beat David," he said.
"I don't want think that it's a mentality problem. If I had a mentality problem, I think I wouldn't have won the first two sets."
Her 66-minute victory meant Sharapova has now dropped just nine games in total, the fewest number conceded by a semi-finalist at the tournament.
The world number two, along with defending champion Azarenka and 15-times grand slam winner Williams, have been a class above the rest of the women's draw at Melbourne Park with few now expecting anyone other than the trio to win the title.
Sharapova has refused to get too far ahead of herself, dragging out the "one match at a time" cliché after each round, though she said after her demolition of Makarova that she was pleased she was staying mentally switched on during matches despite their one-sided nature.
"That's always one of the toughest things, keeping that focus, especially when you have when you feel like you're doing the right things and you have your opponent in the right position," Sharapova said.
"You really have to follow through with what you've done and keep doing it (and) keeping your head in the right direction."
Li Na, meanwhile, showed she had the legs to go the distance when she booked her place against Sharapova in four years with a 7-5 6-3 victory over fourth seed Agnieszka Radwanska.
Radwanska had come into the contest on a run of 13 successive wins but looked underpowered as she was bludgeoned into submission by Li in their tight 102-minute contest.
"I really don't know what it is here," the sixth seed said. "It seems whenever I come down here my results are always quite consistent, no big setbacks or anything.
"I'm not sure whether it's the winter training but it does seem like I'm just better at this tournament."
Radwanska, who had not lost a set on her way to the quarter-finals, said it was possible that she had paid the price for playing and winning warm-up events in Auckland and Sydney.
"I could feel I was playing already a lot of matches. But of course playing every second day helps a little bit that I could rest between the matches," she said.
"But definitely I think I wasn't fast enough today. Especially from the beginning of the match, I was really running a lot. It cost me a little too much power in the beginning of the match."
Novak Djokovic showed no signs of any lasting fatigue to overcome Czech fifth seed Tomas Berdych 6-1 4-6 6-1 6-4.
The world number one, bidding to become the first man to win three successive Australian Open titles since the game went professional, had been forced into a marathon five-set, five-hour fourth round clash against Stanislas Wawrinka on Sunday.
Berdych had felt that energy sapping clash could give him an opportunity to secure his second career win over the Serb and first since their Wimbledon semi-final in 2010.
Djokovic, however, bounced on his toes throughout and effortlessly scrambled and slid across court to wrap up victory in two hours, 31 minutes and set up a semi-final clash with Spain's David Ferrer.
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