Naomi Osaka carries off-season illness into United Cup debut

Naomi Osaka revealed an off-season illness hindered her 2026 debut against Maria Sakkari, the former world No. 1 suffering a 6-4, 6-2 defeat that helped Greece clinch a 2-0 win at the United Cup on Friday.

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“I'm not operating at the percent that I want to be operating at, which kind of sucks because, like, I had a really good off-season so I thought I was going to do really well here,” Osaka told press after the match. “Then I got really sick. I think I'm at the tail end of that, but still not amazing.

“So yeah, I feel like for me, I'm just trying to get better every day. Obviously, I had a cough, like a runny nose, like all that nasty stuff, yeah. Hopefully it goes away before the Australian Open.”

The four-time Grand Slam champion jokingly blamed daughter Shai for the illness, confirming she had been suffering symptoms since “before Christmas Eve.”

“It's been tough. Also for me, that's why I also really appreciate being here because you feel the team atmosphere, it makes you want to go out and do your best and do something. I feel very apologetic that I couldn't get the win,” Osaka said.

“I don't know, we're all here to try our best. If it doesn't work out, it sucks, but we're going to just try again another day.”

Nerves and rust also affected her performance as she lost serve five times against Sakkari, who improved to 2-3 in her head-to-head against Osaka.

“My hand was shaking a little bit,” Osaka said. “That's definitely from my end that comes the first match of the year or if I have a long break or something so...”

Playing her third season since becoming a mom, Osaka took strong momentum into the 2025 off-season after reaching her first Grand Slam semifinal in over three years, stunning world No. 3 Coco Gauff en route to the last four of the US Open. Though she lost a pair of one-off matches to world No. 1 Aryna Sabalenka in December, Osaka looked in position to continue her climb back up the rankings after finishing last season at No. 16.

“I feel like I definitely could have been more aggressive on the returns,” said Osaka. “I think I did that a little bit towards the end. But learning not to be afraid of mistakes and kind of just going for it from the beginning.

“Then also just trying not to be so predictable, which is something that I knew about myself since US Open. Again, I'm kind of afraid to make mistakes. So just trying to, like, break that limitation in my mind.”

Osaka, alongside partner Shintaro Mochizuki, will be back in action on Sunday when Japan takes on Great Britain for their second match of the week.