Svetlana Kuznetsova of Russia celebrates vanquishing Karolina Pliskova of the Czech Republic in their WTA Finals roundrobin match on Wednesday in Singapore. [Photo/Agencies]

After her courtside haircut on Monday, Svetlana Kuznetsova has won a legion of new fans but drawn the ire of her stylist.

"I took the headband off (after the match) and I was like, 'it looks weird'. So I made a picture and I sent it to my hairdresser, sorry.

"He was like, 'I (am) going to kill you'."

The Russian raised eyebrows on Monday when she gave herself a courtside haircut during a break in a difficult match against WTA Finals defending champion Agnieszka Radwanska.

Kuznetsova went on to win the match.

She later said her long ponytail was obstructing her vision and asked the umpire for a large pair of scissors, which she used to chop at her blonde locks.

A video of the impromptu trim posted on her Instagram page garnered 21,000 views in two days.

"It doesn't look so good, but if I tell you the truth, I didn't dry it and look at it properly because I don't want to be really depressed," she said.

Asked by a fan what a movie of her remarkable past week would be called, she deadpanned: "Life of A Hustler."

On Wednesday, Kuznetsova produced another extraordinary comeback to win her second straight match at the WTA Finals, sealing a place in the semifinals.

Just two days after she saved a match point to defeat Radwanska, Kuznetsova again rallied from the brink to beat US Open finalist Karolina Pliskova 3-6, 6-2, 7-6 (6) at Singapore's Indoor Stadium.

With sweat pouring from her face and her muscles aching after she had run herself ragged for more than two hours, the 31-year-old Kuznetsova triumphed through sheer willpower and nerves of steel.

"I play with my heart. I always do," she said. "But maybe I'm starting to believe a little bit more than before. I just hang in there more.

"Some things get together and you get confidence. I see opponents fear me more than before because I win matches, I fight, and I'll be there.

"It doesn't matter if I play like crap and I'm sore, I will just be there competing."

Kuznetsova still has another round-robin match to play on Friday against Garbine Muguruza but is already assured of finishing atop the White Group standings after Muguruza lost 7-6 (1), 6-3 to Radwanska in Wednesday's late match.

Muguruza is out of contention after losing her first two matches, leaving Pliskova and Radwanska to square off to decide who else goes through from the group.

With Serena Williams and Maria Sharapova both absent from the prestigious end-of-season championship, Kuznetsova has emerged as the unlikely headline act of the $7 million tournament, restricted to the world's top eight players.

She defied the odds just to qualify for the tournament for the first time since 2009, only sneaking into the elite field after winning the Kremlin Cup in Moscow last Saturday, then hopped straight on a plane and made the long flight to Southeast Asia.