The poster girl of the Games, who lit the Olympic flame at last week’s opening ceremony, had been favourite for the gold medal after world no1 Ash Barty’s equally surprising exit on Monday, but was denied a quarter-final place as Vondrousova triumphed 6-1, 6-4.
After being broken in her first game, Osaka looked to have shaken off the cobwebs and set up an immediate chance to hit back, but Vondrousova stood firm to hold serve and then steered a wonderful, off-balance backhand winner up the line to bring up three break points in the next game, taking the second of them to go 3-0 ahead.
One exchange in the fourth game summed up the two players’ contrasting starts as Vondrousova engineered another awkward, reaching winner on the run before Osaka planted a simple backhand into the centre of the net and threw her head exasperated towards the heavens, or rather, the underside of the Centre Court roof.
With action on the outside courts postponed due to the rain, a sizeable number of media and staff had gathered inside the showcourt, and there was nervous applause among the Japanese contingent as Osaka finally got on the board, but it only served to delay the inevitable as the Czech took the first set 6-1.
A resurgent Osaka looked to have sharpened up at the start of the second set and quickly went 2-0 up but a trademark drop shot from Vondrousova forced the Japanese to deuce on her own serve soon after and Osaka wobbled again, double faulting to gift back the break.
At 3-3, there were more false signs of recovery as the US Open champion put Vondrousova under pressure at 15-40 but once again her drop shot got her out of trouble, two glorious efforts teasing Osaka all the way to the net.
The home favourite was never going to go out without a fight and serving to stay in the competition she saved two match points but could not manage a third, firing a backhand wide to confirm another shock result at a Games that has already been full of them.