Russian star embroiled in French Open furore: 'Unsportsmanlike'

Tennis fans have taken aim at Veronika Kudermetova after accusing the Russian player of an "unsportsmanlike" act in her French Open quarter-final against compatriot Daria Kasatkina.

Kudermetova went down 6-4 7-6 (7-5) against her fellow Russian, who booked a place in her first semi-final at a major tournament.

'DISAPPOINTING': Iga Swiatek upset with legend's take on women's tennis

'IT'S A JOKE': John McEnroe rips Nadal during Djokovic clash

'MY GOD': Camila Giorgi's father caught in the act at French Open

However, Kudermetova sparked controversy when she decided to take a medical timeout at 6-5 up in the second set - with Kasatkina preparing to serve to force a tiebreak.

It was the second time in as many matches the Russian had called a timeout to deal with an apparent foot injury, with many questioning the timing of Kudermetova's break.

New York Times Tennis writer Christopher Clarey led the backlash against the player after suggesting that players should not be allowed to take medical timeouts at such crucial junctures in a match.

“Basically, unless you need emergency medical assistance, you should not be allowed to take a medical time-out before your opponent serves to stay in a set or win a set," Clarey tweeted.

“Tennis is a game of rhythm and routines. A non-emergency medical time-out is, tactical or not, a significant break in your opponent’s rhythm and routine. Uncool. Unsportsmanlike.”

His views were shared by numerous viewers who also hit out against Kudermetova on social media.

Daria Kasatkina wins battle of the Russians

Kasatkina, the 20th seed, eventually held serve before prevailing in the second set tiebreak to book her maiden grand slam semi-final berth.

The 25-year-old has never managed the last four in any grand slam before and prevailed in front of partly empty stands after a previous late night on Court Philippe Chatrier for the Rafa Nadal-Novak Djokovic epic.

World No.29 Kudermetova peppered the vast Philippe Chatrier stands with the ball and ultimately paid the price for a scrappy performance with 50 unforced errors - double that of Kasatkina.

"You could see that the match was a really nervous one and tight, especially the tie break," said Kasatkina, who missed four consecutive match points before finally sealing the win.

"It' s a very important win for me and I am happy to be in the semis for the first time. I tried to forget about the games I had lost. It is so mental but am happy that I was able to keep it."

Kasatkina next faces top-seed Iga Swiatek, who disposed of American Jessica Pegula in straight sets.

The World No.1 shook off early nerves to extend her winning streak to a staggering 33 matches, courtesy of the 6-3 6-2 victory.

Swiatek, 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.

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

"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 Swiatek on a sunbathed, yet windswept Court Philippe Chatrier.

"Sometimes stress is a positive thing, it's going to make you more active and more tense, so you can play a good performance. So I tried to use it that way."

American Coco Gauff will take on Italian Martina Trevisan in the other semi-final.

with agencies

Click here to sign up to our newsletter for all the latest and breaking stories from Australia and around the world.