Watson poses with her US Open trophy after her impressive performance
Heather Watson became the first Briton to claim the US Open girls' singles title when she beat Yana Buchina in straight sets at Flushing Meadows.
The 17-year-old from Guernsey overcame her Russian doubles partner 6-4 6-1 to win her first junior Grand Slam crown.
Watson, who is based in Florida, found herself 3-1 down in the first set before winning four games on the trot.
The British number one, the 11th seed, then broke at the start of the second set as she eased to an impressive win.
Unseeded Buchina, a 17-year-old from Moscow, had reached the final by beating Britain's former junior Wimbledon champion Laura Robson in the last four.
But Watson, who emulates Andy Murray's US Open junior triumph in 2004, proved just too powerful.
"It feels great," she said. "It's such a great achievement, I'm really pleased and it's great for British tennis."
Buchina started the match strongly, breaking Watson's serve in the third game and then moving into a 3-1 lead.
But Watson, who knocked out second seed and Wimbledon champion Noppawan Lertcheewakarn in the quarter-finals and then ninth seed Daria Gavrilova in the semis, went on to win the next four games.
Serving for the set, the Briton was broken back but made amends immediately to take it 6-4.
Watson, a quarter-finalist in this year's Australian Open juniors, held the opening game of the second set and broke again to go 2-0 up.
Buchina broke back to 2-1 in the next game, but Watson went on to establish complete control, seizing victory with a big forehand to the Russian's backhand, which Buchina could only net.
Watson now plans to step up her career with a view to climbing up the ranks in the women's game.
"I'll definitely be playing more women's tournaments than juniors," she said.
"But I still want to be able to play the junior Grand Slams next year because I really enjoy playing them but I'm going to start trying to climb the women's ladder now.
"This has given me a lot of confidence and I hope I can take this and use it in my next couple of tournaments."