'She's getting inside her head': Commentator apologises for American's 'surprising' tirade

Jessica Pegula lost her composure in an expletive-laden rant before bowing out of the Miami Open quarter-finals against Elena Rybakina on Thursday (AEDT).

The American fifth seed dominated the first set 6-2 before the Australian Open champion began her fightback.

Pegula won a marathon eighth game of the second set to cut Rybakina's lead to 5-3 but her frustrations against the world No.2 from Kazakhstan still boiled over.

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"It's four f---ing overheads," Pegula fumed as she walked over to vent to her coaches, Mark Knowles and Mark Merklein.

Knowles did her best to calm the 32-year-old down.

"It's OK, it's OK. Put it behind you, you're playing better. You're going to do this. You're going to do it," he said.

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Added Merklein: "All positive. Good energy."

But Pegula wasn't done.

"She does the same play every f---ing time," Pegula said, while pointing at her head and appearing to admit Rybakina had the mental edge.

"Apologies if you're offended by the swearing," commentator Tim White said on Stan Sport's coverage.

"I'm surprised to see Jess react like that, that she's getting inside her head. Music to the ears of camp Rybakina."

Co-commentator Lucie Ahl agreed.

"Just frustrated that she hasn't been able to take advantage," Ahl said.

"She's got to try and reset mentally here Pegula."

But the horse had bolted as Rybakina kicked clear for a 2-6, 6-3, 6-4 victory - repeating her win over Pegula at Indian Wells earlier this month.

"I'm putting myself right there," Pegula said after cooling down post-match.

"I'm ­giving myself the chances and the ­opportunities. I think I have elevated my game, I've become a better player. I am definitely challenging them, both of them (Rybakina and Aryna Sabalenka). That's kind of all I can ask of myself and hopefully some of the wins will come along."

Rybakina had previously ended rising Australian Talia Gibson's run 6-2, 6-2 in the round of 16.

Rybakina will meet world No.1 Sabalenka in a mouth-watering semi-final.

Rybakina beat Sabalenka in the Australian Open final in January before the Belarusian got revenge at Indian Wells this month.

"Honestly, for me, it's not really about revenge," Rybakina said.

"I had a lot of opportunities, and it was, in the third set, kind of a roulette in Indian Wells.

"Of course, I just know that we push each other and we can learn from these matches. But I want to come out from the match, no matter the result, being happy with what happened on the court, with what worked.

"Maybe some little improvements, it's already a plus. Hopefully, we play many more times."