LONDON (AFP) - Serena Williams survived a scare to book a Wimbledon semi-final showdown with old rival Maria Sharapova as the world No. 1 battled back to defeat Victoria Azarenka 3-6, 6-2, 6-3 on Tuesday.
Williams was in danger of a shock quarter-final exit after a slow start on Centre Court, but the five-time Wimbledon champion eventually battered 23rd seed Azarenka into submission in two hours and three minutes with a barrage of 43 winners and 14 aces.
The 33-year-old American, aiming to win her fourth successive Grand Slam title and 21st in total, will face world No. 4 Sharapova on Thursday holding a 17-2 lead in their head to head record.
Serena has won all four of her semi-final meetings with Sharapova and defeated the Russian in their previous Wimbledon clash in the last 16 in 2010.
"It's been up and down. But somehow I'm still alive. I don't know how," said Serena, who famously lost to the teenage Sharapova in the 2004 Wimbledon final.
"Maria's been playing really well. I saw her match today. She's such a fighter and it's always good to see her doing well.
"We haven't played each other at Wimbledon in a while but I look forward to it. I just really don't have anything to lose."
After an awkward family reunion in the previous round when she defeated sister Venus in a subdued encounter, Serena was back to her usual shrieking and fist-pumping as she over-powered two-time Australian Open winner Azarenka, who has now lost 17 of their 20 meetings.
Serena's gritty fight-back extended her remarkable winning run at Grand Slams to 26 matches and her 2015 record to a blistering 37-1.
Despite her inconsistent display, Williams, who has won nine of her 11 Wimbledon quarter-finals, remains on course to hold all four major titles at once and is also in the hunt to clinch the calendar Grand Slam by a woman since Steffi Graf in 1988.
She will be heavily favoured to reach an eighth Wimbledon final given her dominance against Sharapova, who will need every trick up her sleeve to beat the American for the first time in 11 years.
Five-time Grand Slam winner Sharapova was forced to swat away claims of gamesmanship during her hard-fought 6-3, 6-7 (3/7), 6-2 last eight victory over Coco Vandeweghe.
She took two hours and 45 minutes before finally defeating unseeded Vandeweghe to reach her fifth Wimbledon semi-final and her first since 2011.
But the 28-year-old was accused of unsporting behaviour by Vandeweghe, who was unhappy that Sharapova was moving during the American's service action.
"She (the umpire) said she didn't believe she was doing it during the motion. I strongly disagreed. Towards the later end of the second set, I said if she has a problem speaking to Maria, if she's too scared to do it, I had no problem speaking to her," Vandeweghe said.
"What I felt from her moving around in between my serving motion was not, I don't think, sportsmanlike. I try to play as fair as I can."
But Sharapova insisted she was doing nothing out of the ordinary.
"It is what it is. What she said, I'm not going to argue against her words," she said.
The other semi-final pits 2012 Wimbledon runner-up Agnieszka Radwanska against 20th seed Garbine Muguruza.
Radwanska, the Polish 13th seed, defeated American 21st seed Madison Keys 7-6 (7/3), 3-6, 6-3 on Court One.
The 26-year-old will be making her fourth Grand Slam semi-final appearance and her third at Wimbledon.
"It cannot be any better. I'm just so happy I could stay in that match. It was very tight," Radwanska said.
"I'm so happy to be in another semi-final."
Muguruza beat Swiss 15th seed Timea Bacsinszky 7-5, 6-3 to become the first Spanish woman to make the Wimbledon semi-finals since Arantxa Sanchez-Vicario in 1997.
The 21-year-old, born in Venezuela but raised as a tennis prodigy in Barcelona, had never before made the semi-finals of a Grand Slam.
"It's just amazing. It was a very tough match and I'm so excited. It was a very intense final game so it's just a relief," Muguruza said.