CNN  — 

A fellow mom gave Serena Williams all she could handle at the US Open but it was the legendary American who battled to another comeback win to keep her hopes of tallying a record 24th Grand Slam title alive.

Williams overcame the varied game of Tsvetana Pironkova 4-6 6-3 6-2 in a thriller in New York to reach the semifinals at her home major for the 11th straight time.

Williams has erased deficits in her last three matches. She trailed by a set to 2017 champion Sloane Stephens in the third round and was behind 2-0 in the third set to Maria Sakkari – who beat Williams at a warmup event preceding the US Open – on Monday.

Afterwards Williams praised the performance of fellow mother Pironkova, saying: “It just shows me how tough moms are – when you can birth a baby then honestly you can do anything.

“I could barely win a match when I came back, so she’s incredible. You play a match and you go home and you’re still changing diapers. It’s like a double-life – it’s really surreal.”

Another mom awaits in the semifinals Thursday after Victoria Azarenka – who has also had some epic contests with Williams – beat Belgium’s Elise Mertens 6-1 6-0. The three moms in the quarterfinals were the most at a major in the Open Era.

Last year’s men’s finalist, Daniil Medvedev, swept past Russian compatriot Andrey Rublev 7-6 (6) 6-3 7-6 (5) to also make the semifinals, where he will play second seed Dominic Thiem, who beat Alex de Minaur 6-1 6-2 6-4.

An ‘amazing’ journey

Serena Williams won her match at the US Open on Wednesday to reach the semifinals.

Williams had to rally from a set and break down against Pironkova, who officially has no ranking after playing her first tournament in three years.

Leaving the tennis tour in 2017, Pironkova gave birth to a son, Alexander, before returning three years later.

Helping her decision was a rule change allowing moms to come back with the same ranking they held when they left, for a certain number of events.

Still, Pironkova’s special ranking sits at 123rd, which in normal circumstances would have meant only a spot in qualifying, not the main draw.

But with qualifying scrapped to limit the numbers on site at Flushing Meadows as part of the US Open’s bubble and other players withdrawing – mostly due to coronavirus concerns – the 32-year-old snuck into the 128-player singles field. There are no fans at this year’s tournament, too.

She eliminated a two-time Grand Slam champion, Garbine Muguruza, in the second round and came close to ousting the 38-year-old Williams in what would have been one of the biggest Grand Slam upsets in recent history.

“So it’s quite a long journey, and it’s been amazing. It still is,” said Pironkova. “I just feel privileged to be here and to be able to play my favorite sport in such a big arena. So it’s amazing.”

Epic rallies

The contest featured several highlight reel rallies, including one of 24 shots in a game that Williams broke in for 5-3 in the second set. Pironkova dragged Wiliams from side to side in the early going, with her opponent doing more of it herself later. The Bulgarian also employed her unorthodox slice forehand.

They traded laser backhands down the line and such was Pironkova’s disguise on her serve that Williams was forced to use her left hand on a return. It led to a break of serve.

“Actually been hitting a little lefty in my practice but not on purpose,” Williams said. “I noticed the other day, I hit a lefty shot and I was just in practice being super intense, and I guess it came through in the match.

“So when you’re in a position like that … this is the quarterfinals of a grand slam, and I was just trying to do everything I can whether righty or lefty.”

The first game of the decider proved pivotal.

With Pironkova holding a game point, she was unable to put away a forehand volley, allowing Williams to rip a pass to finish the point. Williams made her pay by breaking and never trailed again.

Willliams got an insurance break for 5-2 after Pironkova built a 40-15 advantage. She hit 20 aces overall, her most in eight years. The two exchanged a smile at the net when it ended.

Serena Williams, right, and Tsvetana Pironkova exchange a smile after their US Open quarterfinal ended.

Her three-set victories are reminiscent of the 2015 French Open, when Williams won five three-setters en route to the title.

Naomi Osaka, who downed Williams in the controversial 2018 final, faces a surging American, Jennifer Brady, in the other semifinal.

No sets lost for Medvedev

Medvedev still hasn’t lost a set this fortnight.

The third seed came close, though, in the opener, as the big-hitting Rublev led the tiebreak 6-3.

Rublev appears mellow off court but on it he is combustible. The 10th seed threw his racket onto the court in disgust and also threw his banana when the set ended. There was no way back for him against his good pal after surrendering that lead.

Late in the match, Medvedev took a medical time out for what seemed like a right shoulder issue and the trainer later worked on his leg. He’ll hope it’s nothing serious.

Medvedev and Thiem were the lone two men’s quarterfinalists to have played in a grand slam final following the default of heavy men’s favorite Novak Djokovic against Pablo Carreno Busta on Sunday. Carreno Busta has already booked his spot in the semis and takes on Alexander Zverev.

It’s wide open in the men’s draw but with Williams and Osaka still around, the same can’t be said about the women’s draw.