Iga Swiatek's next opponent in her Wimbledon title push is Yulia Putintseva, the diminutive Kazakh who once described herself as "a gangster on court and angel off it".
The 29-year-old Putintseva may only stand at 1.63 metres (5ft 4ins), but there is nothing small about her personality or reputation.
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A three-time Grand Slam quarterfinalist, the Moscow-born player was once advised to seek the help of a psychiatrist by a rival.
An umpire, frustrated by her behaviour on court, even refused to shake her hand at the end of a match.
"I'm like a gangster on court, but like an angel off court," Putintseva told wtatennis.com.
When she faced Swiatek at Indian Wells earlier this year, she was ticked off by the chair umpire for moving from side to side as the world No 1 shaped to serve.
Putintseva even threw in a collection of underarm serves.
"Maybe they teach that in Kazakhstan," said Swiatek.
"I can only be responsible for what's going on with me. I want to keep my standards high no matter what's going on, and I think this match was a test for my mental training that I did."
A former top-30 player with three WTA titles to her name, there is never a dull moment when Putintseva takes to court.
At the 2022 Qatar Open, Victoria Azarenka accused her of cheating when she called for medical treatment just as the former world No 1 prepared to serve for the match.
"She threw her racquet like seven times. She needs a psychiatrist," Azarenka complained to officials.
Six years earlier in Washington, the umpire refused to shake Putintseva's hand at the end of a match in protest at the player's regular complaints over line calls.
"This is my last match with you," said Putintseva.
"I hope so," replied the exasperated official.
Putintseva has a 4-0 losing record to Swiatek and has yet to win even one set.
However, she arrived at the All England Club with the Birmingham grass-court title under her belt.
At Wimbledon, she knocked out former champion Angelique Kerber in the first round before seeing off 27th-seeded Katerina Siniakova.
Putintseva has often defended her temperamental on-court reputation.
"In Russia it was pretty tough. They were saying I'm too short, too pushy, too this, too that. Well, look at me right now," she told wtatennis.com.
She understands why critics see her as having two dramatically different personalities.
"I knew since I was a kid. My father would tell me, 'Yulia, your temper on the court is too much sometimes.'
"But his temper was too much sometimes, too. We were both hard characters when we used to work together. But outside it was a lot of love and chill time. We actually never fought outside the court but all the time on the court."