Naomi Osaka was "confused" but apologetic after a testy exchange and icy handshake at the end of her Australian Open third-round win over Sorana Cirstea on Thursday.
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The four-time major champion from Japan downed the experienced Romanian 6-3, 4-6, 6-2 in Melbourne to set up a clash with Australia's 168th-ranked Maddison Inglis.
But it was far from a vintage performance, with a bumper 41 unforced errors and the match ending with angry words at the net.
"Apparently a lot of 'c'mons' that she was angry about, but whatever," said Osaka in her on-court interview.
"I tried to play well. I think I hit a lot of errors, but I tried my best.
"She's a great player. I think this was her last Australian Open.
"So sorry she was mad about it."
Cirstea, in her 18th and last Australian Open having announced 2026 will be her final season, insisted it was no big deal.
"There was no drama. It was just a five-second exchange between two players that have been on tour for a long time. It stays between us," she said.
Pressed further on whether Osaka's shouts of "c'mon" had bothered her, she refused to be drawn.
"I will not talk about that," she said. "Look, this is my last Australian Open, I've been playing for 20 years, and I think it's a bit more going on than just a five-second discussion at the end that I've had with Naomi."
In her post-match press conference Osaka, who won the Australian Open in 2019 and 2021, said the incident was a first for her.
"I've never been involved in something like this before, so I don't know if we're supposed to leave it on the court and be like, 'Hey, how you doing'?" she said.
"I'm a little confused. I guess that emotions were very high for her. I also want to apologise.
"I think the first couple things that I said on the court was disrespectful. I don't like disrespecting people. That's not what I do."
Osaka laboured to a three-set win in her first round and it was more of the same against the 35-year-old Cirstea.
The 16th seed Osaka was broken immediately with a wild forehand gifting the Romanian, but she made amends with a sizzling backhand winner down the line to earn a break back for 2-2.
Osaka pounced again with a break to love for 5-3 as Cirstea's serve began to let her down and wrapped up the set in 34 minutes.
But Cirstea refused to go away, breaking for a 2-0 advantage in the second set after the world number 17 spilt a backhand wide.
Osaka again responded to level, but she was plagued by errors and the Romanian took it to a decider.
An off-court break revitalised Osaka and she broke straight away to take charge in set three, keeping her foot to the floor to stay alive.