Keys’ power vs. Siegemund’s spins and slices offered quite a contrast in styles, and this outcome was surprisingly one-way traffic on a windy afternoon at No. 2 Court. The key statistic, undoubtedly, was this: Keys made 31 unforced errors, 20 more than Siegemund.

When it ended with one last backhand return from Keys that sailed wide, Siegemund smiled broadly, raised her arms and jumped up and down repeatedly.

“You can’t not be happy when you beat a great player like Madison,” Siegemund said.

How unexpected is this for Siegemund? Before this year, her career record at the All England Club was 2-5, and she’d never made it past the second round. Taking into account all four Grand Slam tournaments, she had reached the third round only once in 28 previous appearances, getting to the quarterfinals at the 2020 French Open.

“There is technically no pressure for me,” said Siegemund, at 37 the oldest woman remaining in the tournament. “I try to remember that I only play for myself. I don’t feel like I need to prove anything anymore. My boyfriend often tells me that.”

On Sunday, the German faces another participant no one could have predicted would be at this stage of the grass-court major: 101st-ranked Solana Sierra of Argentina, who lost in qualifying and made it into the main draw when another player withdrew.