Australian Open: Iga Swiatek and Danielle Collins complete women's semi-final line-up

Top seed Ash Barty and American Madison Keys to contest the other last-four clash at Melbourne Park

Iga Swiatek celebrates her victory over Kaia Kanepi in the Australian Open quarter-finals. AFP

Iga Swiatek battled back from a set and a break down to defeat Kaia Kanepi and book an Australian Open semi-final showdown with Danielle Collins on Wednesday.

The Polish seventh seed needed to call on all of her resilience to get over the line, ending the unseeded Estonian's Melbourne Park run 4-6, 7-6, 6-3 on Rod Laver Arena in an exhausting match that lasted just over three hours.

Swiatek will play Collins on Thursday for a place in the final after the American 27th seed ground down Alize Cornet 7-5, 6-1 to match her Australian Open exploits from 2019.

The 20-year-old Pole is in the second week for a sixth consecutive Grand Slam since her 2020 French Open triumph, but it the first time she has made the last four away from the Paris clay. Ranked No 9, Swiatek is now projected to move up to fourth in the world and could go as high as No 3 if she wins the title.

"I had so many break points [nine] in the first set that I felt like I missed my chances," said Swiatek. "I was pretty annoyed and I should have been focused on the next point. And that's what I did in the second set exactly that.

"They are easy things to do but they are working. I felt like she was playing so fast that I couldn't be tight. so I had to finish my forehands basically. That was enough."

For Collins, reaching a second Australian Open semi-final would have been a tall order from where she was 12 months ago.

The American was in a dark place last year while suffering severe abdominal and back pain during her periods that impacted her ability to train and play, which led to a diagnosis of endometriosis.

Collins had surgery last April and it has been a long road back to her first Grand Slam semi-final since 2019 in Melbourne. She is the second American into the Melbourne Park semi-finals, with compatriot Madison Keys set to face top seed and home favourite Ashleigh Barty in the top half of the draw.

"When you're dealing with that type of physical pain multiple weeks out of the month, you're not putting yourself in a position to be able to perform consistently and to be at your best whether as an athlete or a person," Collins said.

"I think I certainly feel a lot freer just not having to deal with the symptoms that I used to deal with, that not being a continuous issue that I'm dealing with on a daily basis."

Collins' fitness was on full display during a sweltering morning match at Rod Laver Arena, the 27th seed ramping up the aggression to blow Cornet off the court in the second set.

She showed no nerves as she hammered a forehand down the line to earn two match points, then sealed it when Cornet thudded a forehand into the net.

"It feels incredible," said Collins. "Especially after some of the health challenges I've had. To be able to compete with these women, it's such an honour."