British number three Heather Watson gave third seed Maria Sharapova a huge fright in the opening round of the US Open before going down 3-6 7-5 6-3 in Arthur Ashe Stadium.
The 19-year-old from Guernsey, making her first appearance in the senior draw after winning the junior title two years ago, led by a set and a break early in the second set but found Sharapova just too strong in the end.
The Russian is second favourite to win the women's title behind Serena Williams and has been on a superb run of form, reaching the final at Wimbledon and winning the warm-up tournament in Cincinnati.
But Watson made a great start and after winning the opening set things looked even better for the British girl when she broke again at the start of the second set. But it was inevitable Sharapova would respond strongly and she did just that.
The British player began to drop her shots a bit too short, allowing the Russian to step inside the court, and she powered her way to four games in a row.
The tide had very much turned but Watson is made of stern stuff and she dug deep to stop the rot before getting back on serve when Sharapova threw in a sixth double fault.
Things looked ominous when the British player slipped to 0-30 serving to stay in the set but again she would not let Sharapova get away. However, there was nothing the 19-year-old could do when her opponent piled the pressure on again two games later.
Sharapova, who had won all 11 of her previous three-set matches this year, had cut down the errors substantially and she made it four games in a row with a break at the start of the decider.
Watson got on the board with a gutsy hold for 3-1, and there was a glimmer of hope when she broke the 2006 champion to get back to 4-3, but Sharapova responded straight away and this time there was no way back.
Laura Robson advanced to the second round when Japanese opponent Ayumi Morita retired with the British teenager leading 7-6 (7/5) 1-0.
Morita called for the trainer after the first game of the second set and, after a brief assessment of what appeared to be a right shoulder injury, she decided she could no longer continue.
During the hour and one minute of play, 17-year-old qualifier Robson competed well with Morita, ranked 46th in the world, and had just broken the Japanese player's serve for the fourth time when play was halted.
Petra Kvitova became the first reigning Wimbledon champion to lose in the first round of the US Open in the Open era when she went down 7-6 (7/3) 6-3 to Alexandra Dulgheru of Romania.
The Czech has had a difficult time since beating Sharapova in the final at the All England Club in July, winning only two matches.
In contrast, world number 49 Dulgheru played a very solid match and, after breaking Kvitova to lead 5-3 in the second set, she served out the victory to love.
Germany's Julia Goerges, the 19th seed, eased to a 6-3 6-2 victory over compatriot Kristina Barrois while Lucie Safarova came from a set down to beat Magdalena Rybarikova 2-6 6-3 6-2.