From the carefree way that Jelena Ostapenko smacks a tennis ball, you would think no one was watching. Yet the unknown Latvian thrilled 15,000 fans on Court Philippe Chatrier, and millions of TV viewers, as she became the youngest grand slam champion since 2006.

Judging by her on-court interview, Ostapenko was as bewildered by her triumph as everyone else. She arrived here as the world No 47, hoping to get through a couple of rounds, or reach the second week at best. Her pre-tournament odds were 100-1, so this 4-6, 6-4, 6-3 victory over Simona Halep made her the most unlikely major winner that modern tennis has produced.

Now Ostapenko goes away with the Coupe Suzanne Lenglen, and the small matter of £1.8 million in prize money. This was the eighth major she has competed in, and she only turned 20 during Thursday’s semi-final against Timea Bacsinszky. But by succeeding so spectacularly, she has already achieved a goal that eludes Caroline Wozniacki, Jelena Jankovic and Dinara Safina – all former No 1s who have never won a grand slam.

“I still cannot believe it,” said Ostapenko, “because it was my dream and now it came true. I think I’m going to only understand that in maybe couple of days or couple of weeks. Five or 10 minutes before the match, I was a little bit nervous, and then again when I was losing the second set. But then I felt I have nothing to lose, so I’m just going to enjoy the match and do my best.”