When Zheng carved out a breakpoint on Osaka's first service game in the second set, the Japanese responded with a cracking forehand winner on the sideline and a pair of booming first serves.
But Zheng’s old-school game was making headway. She gained three more chances to break the Osaka serve at 1-all. The first two were squandered with errors, before Osaka gifted the game with two wayward backhands and flung her racquet to the court in disgust.
It was the first of a flurry of service breaks. When Osaka again fell behind for 2-3 on an overplayed forehand, she went not for racquet-throwing this time but a stony-faced look at her box and a sarcastic racquet-clap.
Serving at 3-2, Zheng was now controlling the points for the first time, pulling Osaka deep and wide and forcing errors. She held to love when Osaka netted an off-kilter backhand.
At 4-2, with Zheng appearing in control, Osaka again rose with the threat, pummelling her big returns, breaking back to love and dictating play for the win.