Chinese ace Zhang Shuai's tearful retirement over a disputed line call during a WTA 250 match has earned overwhelming support from her peers, with her opponent's ill-mannered behavior condemned by the tennis world.

Desperate to curb her recent singles losing streak, Zhang suffered another setback on Tuesday at the clay-court Hungarian Grand Prix, with the Chinese veteran retiring midway through her opener against local wild card Amarissa Toth due to an emotional meltdown sparked by the controversial ruling and her opponent's conduct.

The drama began with Zhang serving at 15-all, 5-5 in the first set. Zhang hit a crosscourt forehand winner to the corner of the service box, which TV pictures showed had left a clear mark on the line. However, the shot was called out by French umpire Morgane Lara, who upheld her ruling after leaving her chair to check the mark upon Zhang's request.

So convinced that she hit the line to score, Zhang went back and forth with the chair umpire for several minutes seeking further explanations. She then complained, "Oh my god. I cannot keep playing this way!" after the official stood by the call, with the TV commentator agreeing that it looked a good shot on the review.

"Tell me it's out! Tell me! If you say this one is out, it's over!" Zhang continued to argue as the partisan home crowd jeered.

Zhang, a three-time WTA singles title winner, calmed herself down to win the next point, but the tension escalated after the 20-year-old Toth tied the game 30-all and promptly erased the mark from the disputed point at 15-all.

"Wait, wait, keep the mark! What are you doing? Why would you do that?" Zhang protested.

"Because you're making problems, that's why," replied Toth, who is ranked 349th in the world and was making her WTA debut at the Budapest tournament.

Zhang, a two-time Grand Slam doubles winner with Australia's Sam Stosur (2019 Australian Open, 2021 US Open), went on to lose the game, and it all became too much for the 34-year-old to continue.

Zhang called for a physio at the changeover, and then wept as she spoke with a tournament supervisor before deciding to retire.

She maintained her grace to shake hands with the chair umpire and Toth, who immediately raised her clenched fists in celebration as Zhang left the court in tears.

"All efforts on practice was wrong, because when you wanted hitting closer to the line, even touched the line still OUT," Zhang wrote on her Instagram account after the match.

"I love you guys and all girls who supporting me and standing (by) my side," added the world No 28.

The behavior of Toth, who at one point was seen laughing at Zhang's protestations, drew a huge backlash from fans and players on the tour, with one even calling her the "most unsportsmanlike" athlete this year.

Australian doubles star Ellen Perez was among the first to declare her support for Zhang, who by all accounts is a popular figure on the circuit.

"Well that's a quick way to lose respect from your peers. I'm actually shook by the level of disrespect from this girl," Perez tweeted about Toth. "If I see this girl tomorrow I will tell her how disgusted I am."

Perez said she watched the full replay and was "furious" with how it all unfolded, including from the chair umpire's perspective.

"The ball is clearly in and at such a tight moment there is zero per cent chance you don't fight this until the death. Then you have the crowd yelling at you," said the doubles world No 9.

"Then you have the girl laughing at the situation, then you have her yelling the biggest 'Come on', then you have her erase the mark after being asked not to and with attitude saying you're making it a problem, then her celebrating the win, then her implying she would have won anyway.

"There's only so much one can handle before the blood is boiling and emotions get the better of you. I am not even on the court and legit fuming at this whole situation."

Australian doubles great Rennae Stubbs also interrupted her post-Wimbledon vacation to side with Perez's take on the furor.

"And that umpire needs to find another job ASAP! She also should be getting hammered for this," Stubbs wrote.

Another Aussie ace, Ajla Tomljanovic, also spoke up for Zhang, describing Toth's laughter and wild celebration as "absolutely disgusting behavior" on Twitter. "Shuai is a better person than a lot of us for shaking the ref and that girl's hand. But then again it's Shuai we are talking about, of course she did," said Tomljanovic.

Belgium's Ysaline Bonaventure said it was "a shame" to see Toth celebrate Zhang's tearful retirement, while Polish veteran Urszula Radwanska tweeted: "The award for unsportsmanlike conduct of the year goes to Amarrisa Toth."