The 15-year-old American Cori Gauff produced one of the biggest opening-day upsets in Wimbledon history on Monday as she upended five-times champion Venus Williams 6-4, 6-4 in the first round.

The teenager, the youngest player ever to qualify for the main draw, played brilliantly throughout and kept her nerve as she ousted the 39-year-old on Court No 1 in what was her debut performance in a grand slam event.

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As Williams’ final forehand fell short in the net, Gauff crouched down at the back of the court, head in hands. “Honestly I don’t really know how to feel,” she said. “This was definitely the first time I ever cried after winning a match. I don’t even know how to explain how I feel.

“I had to tell myself to stay calm, I’d never played on a court so big. I had to remind myself that the lines are the same size.”

Williams had won four of her seven grand slam titles before Gauff, nicknamed Coco, was even born. The 15-year-old, who won the junior title at the French Open 12 months ago, has been tipped for the top for some time and she didn’t disappoint, serving beautifully, covering the court with effortless ease.

Serena Williams had said that Gauff reminds her of Venus, athletically, and the youngster took the attack to Williams from the off. She broke for 3-2 in the first set, held serve in the next game thanks to a drop shot and held the advantage to take the set.

Gauff broke again in the fifth game of the second set and the only time she showed any sign of nerves was when she dropped serve for 4-4. But she bounced back immediately to hold for 5-4 and though Williams saved three match points, she dumped a forehand into the net to hand the 15-year-old the win.