Women's world number one Iga Świątek made it 33 wins in a row with a 6-3, 6-2 quarterfinal victory over America's Jessica Pegula as she romped into the final four in Paris.

Świątek, who turned 21 on Tuesday, is on the longest unbeaten run on the women's tour since Serena Williams bagged 34 victories in succession in 2013, a year where she won both the French and US Open titles.

Williams's run pales in comparison to the longest of all-time on the WTA Tour and is held by Martina Navratilova, who won 74 matches straight in 1984.

The Polish player, gunning for a second title in three years at Roland Garros, appeared a tad shaky in the initial games before marching past the 11th seed to set up a meeting with Russian Daria Kasatkina for a place in Saturday's final.

The 2020 champion is bidding to become the fourth player since 2000 to lift the Suzanne Lenglen Cup multiple times after Justine Henin, Serena Williams and Maria Sharapova.

Świątek admitted to nerves early in the match but said for her, they and Pegula's power game helped her focus.

"She was playing very low so to be good I had to be low on my legs. It was the key and I'm pretty happy I was playing with a good dynamic to push her back a little bit," said Świątekon a sunbathed, yet windswept court Philippe Chatrier.

Two days after dropping her first set of the tournament to Chinese teenager Qinwen Zheng, Świątek got off to a fast start, breaking Pegula's serve with a crosscourt forehand winner.

But unforced errors immediately crept up in her game and she was immediately broken back and showed early signs of nerves.

Świątek, however, went up a break again to lead 4-3 before holding and setting up set points in the ninth game. Pegula did her a favour by sending a routine forehand wide on the second.

Another of those gave Świątek a break for 3-1 in the second set and she kept her grip, only squandering three match points before wrapping it up on Pegula's serve with a booming backhand winner down the line.

Her opponent in the semifinals will be Russia's Daria Kasatkina, who is at this stage of a slam for the first time after she defeated countrywoman Veronika Kudermetova 6-4, 7-6 (7-5).

Kasatkina though is yet to drop a set in the tournament and the second set tiebreak against Kudermetova is the closest she has been pushed.

She said nerves played a part in that.

“You could see the match was really nervous inside, especially the tiebreak, the last few points were super tight. I’m happy in the end, it’s a very important win for me. I’m happy to be in the semis for the first time," she said.

As to what she thought helped her get there? The answer was a bit stranger, as she thanked a not so healthy snack for being a regular part of her French diet.

"If you play good, you have to treat yourself. Even if you are not playing good it's not bad to treat yourself, because you are pushing and you are trying."

Świątek and Kasatkina will do battle on Thursday before American teenager Coco Gauff and Italian surprise packet Martina Trevisan square off in the other semifinal.

ABC/Reuters