It was a great day for Japan's Naomi Osaka, who rolled past first round opponent Zheng Saisai of China 6-1, 6-4. It was Osaka's first match -- and victory -- in nearly two months.

Belting six aces in sweltering conditions, the World No. 2 closed out her opener in just over an hour and a half. Though she struggled a bit in the second set -- unable to move past deuce on several occasions -- Osaka managed to stay focused and hold her nerves while on Centre Court.

"I'm super excited to be here," Osaka said in a post-match interview, explaining that -- at times -- she felt like "a giraffe on ice." She also referred to lighting the Olympic cauldron as "the greatest moment of my career, definitely. For me, it means more than winning a Grand Slam."

More good news for the four-time Grand Slam champion: Australia's Ashleigh Barty -- the World No. 1, and arguably Osaka's biggest potential opponent at these Games -- crashed out of the tournament in her Olympics debut.

Next, the Japanese star will play Switzerland's Viktorija Golubic in singles round two.