British teenager Heather Watson gave former champion Maria Sharapova an almighty scare before the Russian prevailed on day one of the US Open.
Watson, 19, led 6-3 5-5 at one stage but eventually went down 3-6 7-5 6-3 in a dramatic match at Flushing Meadows.
The Briton had been given little chance against Sharapova, ranked 100 places higher at fourth, but almost produced one of the great US Open shocks.
Watson's fellow Briton Laura Robson earlier made it through to round two.
Robson with a shoulder injury, but it was Watson's performance that took centre stage on Monday.
"I had a lot of fun today," said the teenager from Guernsey. "It's what I want to do. I want to be out there on the big courts playing the top players. It was a really great match, very competitive. We played some really great tennis.
"I had my chances in the second set. You have to create the opportunity but also execute, and I was probably a bit too defensive on those important points.
"But I always believed I could win. There's no point in my going out there if I don't believe that I can win."
Watson, the 2009 junior champion, was playing in the US Open main draw for the first time, but despite it being the highest-profile match of her life she took to the imposing surroundings of Arthur Ashe Stadium like a natural.
Sharapova, seeded third, was widely seen as the second favourite for the tournament behind Serena Williams, but the erratic serving that has blighted her this year was still in evidence.
Watson needed no encouragement, standing close to the baseline and going toe-to-toe with the Russian's heavy groundstrokes, and she broke to love at the first opportunity.
When Sharapova broke back immediately it seemed the former world number one was about to take control, but another double-fault handed the advantage back to the Briton and she did not relinquish it.
After converting her third set point in game nine, Watson immediately broke at the start of the second set and it was panic stations for Sharapova.
The decibel level increased with the pace of the Russian's groundstrokes and she bludgeoned her way back to parity before the power began to tell and she moved 4-1 clear, but it was not totally convincing and her sixth double fault of the day brought Watson back on serve.
Three superb points got Watson of trouble when she served at 5-4 down and 0-30, but Sharapova made the breakthrough at the next opportunity to level at one set all.
Watson's resistance was far from over and it took a marked improvement in Sharapova's form for the 2006 champion to finally dominate, battling into a 4-1 lead and having break points for 5-1.
The 24-year-old could not quite shake off the Briton, however, and was pegged back to 4-3 before a fine return game gave Sharapova the chance to finally serve for the match.
Few can have expected Watson to keep such an illustrious opponent on court for two hours and 34 minutes but that was how long the Russian required to close out the victory.
"It was one of the toughest (opening matches) that I've had," said Sharapova. "Obviously not really knowing too much about my opponent and not facing her before, she just came out and played really smart.
"There's no doubt that I wasn't playing my best tennis. She was smart in making me hit another ball. I was making so many errors out there. She stuck to her game plan. She kept grinding."