Osaka, a two-time champion at Flushing Meadows, came up against a player in fine form in Muchova, with the Czech displaying the quality that saw her reach the semi-finals a year ago.

"I was just really trying to be focused," Muchova said.

"I know she's an amazing player and that I have to bring the A-game to have a chance. So I was just trying to be really focused on myself. I knew I had to serve well because her serve is really good. So I was just trying to be kind of locked in myself and focused out there."

"Then the energy and the big court and all that, it for sure helps me. I like that."

Osaka, meanwhile, suggested the nerves got to her on Arthur Ashe Stadium.

"I think during the pressure moments I got nervous," Osaka said, "and I don't know if I just have to keep playing more matches and get used to that feeling, especially on a really big stage.

"Honestly, if I get past the disappointment, I feel pretty proud of myself to have gotten that many opportunities while still feeling like I could have played much better."