Indian Wells is known as the unofficial fifth Grand Slam, and with it brings the drama and controversy of a big tournament.

The second-round clash between Donna Vekic and Lesia Tsurenko was no exception, with Tsurenko coming back to win in a shock upset over the world No. 23.

Watch Tennis Live with beIN SPORTS on Kayo. Live Coverage of ATP + WTA Tour Tournaments including Every Finals Match. New to Kayo? Start your free trial now >

Tsurenko, ranked 95th in the world, had to qualify for Indian Wells this year, but came back from a first-set 2-6 loss to win 2-6, 6-2, 6-2.

Post-match formalities were frosty, however, with Vekic refusing to shake hands.

Tsurenko walked over to the net at the conclusion of the match, as is customary, but without being met by Vekic.

In an apparent attempt to move past the snub, Tsurenko then went over to Vekic’s side of the net to offer her hand, but was roundly ignored.

The Croatian packed her bags and left the court quickly without acknowledging Tsurenko.

Social media blew up over the Monterrey Open winner’s snub, with fans on Twitter calling it “poor sportsmanship”.

“Backstory doesn’t matter,” said one fan.

“Vekic should have shook Tsurenko’s hand after the match.”

Another said it was “complete disrespect”.

“Being a sore loser is one thing, but refusing a handshake is a complete disrespect towards the opponent.

“Completely unacceptable.”

A fan account for Donna Vekic on Twitter said that Tsurenko had been “acting like (she was) about to retire after every point to slow the game”, and that she’d been “doing it for years.”

Broadcaster David Law said Vekic “was not having any of it today” on the Tennis Podcast.

“She kept that intensity even after the match had concluded. What a competitor,” he said.

Tsurenko has lost by retirement or walkover in eight of the last 17 WTA tournaments she’s competed in since last year’s Masters.