Jelena Ostapenko overpowered title favourite Simona Halep to become one of the most surprising grand slam champions of all time.
The 20-year-old, ranked 47, had never been beyond the third round at a grand slam before nor won a senior title.
But she was unfazed, hitting 54 winners in a 4-6 6-4 6-3 victory to become the first Latvian ever to win a grand slam singles crown.
Ostapenko is the first unseeded player to win the women's singles title at Roland Garros in the Open era.
When she drilled a final backhand winner down the line, Ostapenko dropped her racket to the clay and held her arms aloft in delight and disbelief.
She said: "I think I cannot believe I'm the Roland Garros champion. I'm only 20 years old. I'm really happy. I have no words, it was my dream."
Ostapenko had blasted her way into the final on the back of 245 winners - more than any other player in the draw, man or woman.
But Ostapenko had made nearly as many errors and the challenge for her was to keep the ratio in her favour.
This was the classic contrast of styles, with Halep a superb mover and defender, but ultimately aggression won out.
What was most remarkable was how Ostapenko defied her lack of experience to fight back from a seemingly hopeless position.
Halep, beaten by Maria Sharapova in the final here in 2014, had been the favourite from the start pf the tournament and looked to be cruising at a set and 3-0, with points for 4-0.
But Ostapenko trusted in her game and then came from behind again in the decider, winning the final five games.
She said: "I knew SImona is a great player and she was playing great. I was just trying to stay aggressive.
"I was missing but a couple of games were decisive and everything turned my way. Even in the third I was 3-1 down but I tried to fight for every point."