Kimberly Birrell was left speechless after pulling off the biggest upset at the French Open so far when she stunned world number five Jessica Pegula in three sets.

Birrell had never before won a match at Roland-Garros – or at any major besides the Australian Open – but she erased a set and a break deficit to book her place in the second round.

Pegula became the highest-ranked player to fall in the opening round, as the number five seed was beaten 1-6 6-3 6-3 in one hour and 41 minutes.

The American had reached at least the third round in each of her last four appearances at the French Open, following back-to-back first-round exits in 2019 and 2020.

Birrell, who now has three top-10 wins under her belt, was thrilled to get her first Roland-Garros victory, having remained patient following a tough start.

"I don't really know what to say or think," she said. "When I saw the draw and saw I was playing Jessie, I knew it would be really tough.

"I really admire her as a player and person. I tried to take it one point at a time. I thought she played so well in the first set. My goal was to just win one game and slowly gain some confidence.

"So happy I was able to play probably the best match I've played on clay, and able to play during a Grand Slam, especially here, it's really, really special."

Pegula won the first four games of the set, and though Birrell broke back, the American wasted little time taking the first.

She then went a break up to take a 2-1 lead, but Birrell immediately cancelled out her advantage before holding off three break points in the next game.

The Australian got another vital break in the penultimate game, going on to force a decider, and though neither player was able to hold onto their serve late on, it was Birrell who came out on top.