Tennis star Yulia Putintseva has made a public apology after being booed by the US Open crowd as she disrespected a ball girl.

The 32nd-ranked Putintseva appeared to take out her frustrations on the ball girl during her third-round loss in an ugly moment that angered fans, tennis commentators and former players.

Video footage, widely viewed on social media, shows Putintseva rudely ignoring the ball girl at Louis Armstrong Stadium and failing to react as two balls were bounced toward her for her service.

The 29-year-old player inexplicably ignored the young girl, allowing the balls bounce off her torso and leg before begrudgingly picking up the third ball.

The ball girl was seen shaking her head in disbelief as she returned to her position at the back of the court.

Putintseva’s petulant behaviour turned support in the stands against her as the crowd first booed, then cheered each point she subsequently lost to eventual winner Jasmine Paolini.

Australia’s Rennae Stubbs said the “obnoxious behaviour” was typical from the Russian-born Kazakhstani, while German great Boris Becker asked: “Who does Putintseva think she is?”

But while Putintseva was roundly condemned, there was plenty of praise for the unnamed ball girl and her professionalism.

“Tremendous effort from the ball girl to raise her arms. Ball persons should never ever get dissed, since so many former players were a ball kid as well,” wrote US commentator Brad Gilbert.

Putintseva eventually posted a response to incident on Instagram, writing: “I want to apologise to the ball girl for the way I was, when she was giving me balls.”

She said her behaviour was not about the ball girl, but rather frustration at winning the previous game.

“I was not even focusing on whats going on and who gives me the ball,” the Kazakhstani said.

“All the ball kids was doing amazing as always at the open.”

The US Open is the only grand slam to pay its ball kids, who receive $US17 ($25) an hour for their services.

At the Australian Open, ball kids are volunteers and receive a prize pack at the end of the tournament.