Cori Gauff overcame a 24-year age gap to stun Venus Williams on her Wimbledon debut.
The 15-year-old American is the youngest woman to qualify for the tournament in the Open era but she played like a veteran in a superb 6-4 6-4 victory.
Gauff served superbly, being broken only once, and showed tremendous composure in her first main draw match at a grand slam, making just eight unforced errors compared to 25 for her 39-year-old opponent.
Williams won two of her five Wimbledon singles titles before Gauff was born and this was only the second time she has been beaten in the first round since her debut in 1997.
While Williams has been setting records at one end of the age scale, Gauff has been breaking them at the other, reaching her first junior slam final at the US Open aged just 13.
She won the French Open title last year and, on this evidence, she is more than ready to make a big impression in the senior game.
Gauff was inspired to pick up a racket by the Williams sisters and for Venus it must have been like facing a teenage version of herself as her opponent fired down serves over 110mph and scampered around the court with her long levers.
Gauff is already a terrific athlete and Williams was simply unable to hit through her. What was most impressive, though, was the way she constructed points, playing close to the lines but rarely too close and using angles to open up the court.
A break for 3-2 set her on the way to the first set without facing a break point and, when Williams double-faulted twice in a row, Gauff, who sat an online science exam at 11pm before her final qualifying match, moved 3-2 ahead in the second.
She seemed to feel the occasion for the first time serving at 4-3, double-faulting to hand back the break, but she forced another break of the Williams serve in the next game to leave herself serving for the match.
A tense game saw Williams save three match points before creating one break point, which Gauff saved with a 108mph second serve. When her fourth opportunity came, the teenager took it, then dropped to the court in disbelief.