NEW YORK (AFP) - Maria Sharapova found out the hard way that for all the work she has done recovering from right shoulder surgery, it will take much more for her to regain the form that made her a world number one.Sharapova sprayed 21 double faults across Arthur Ashe Stadium and made a stunning 63 unforced errors on Saturday in falling 3-6, 6-4, 7-5 to US teen Melanie Oudin in the third round of the US Open. "With the amount of errors I made from both my groundstrokes and my serve, to be able to get it to three sets is not bad," Sharapova said. "If I didn't make those errors, those double-faults, I certainly would have won the match."So that gives me some confidence."Three-time Grand Slam champion Sharapova spent more than nine months off due to her injury, returning in May and slowly rebuilding her game with the year's final major tournament at Flushing Meadows her goal.The effort was squandered when she surrendered eight services breaks to the diminutive American speedster. Now it's back to the drawing board."It's a success in the sense that I'm back out playing tennis and hitting a tennis ball for a living," Sharapova said."I'm lucky enough that I worked that hard to get back to being on the court. I have to work not just as hard but harder to get back to the top." After saving six break points in the fifth game of the final set, Sharapova called for a trainer, who massaged and stretched the 22-year-old Russian's right upper arm muscles, something she said has been a nagging issue. "It has just been an on-going thing," Sharapova said. "I just needed a little warmup out there." Sharapova blamed her serving woes - she connected on only 57 percent of her first serves and won just 16 of 53 second-serve points - on the fact she could not take some speed off her seconds serves."Just couldn't decelerate. I was hitting second serves no less than 95 mph. I even tried to hit it less and I just couldn't," she said. "Considering I couldn't hit a second serve lower than 95 mph, it's pretty difficult." Sharapova would not elaborate on whether her trouble was mechanical or mental, but in either case it was aggravating against a foe that chased down shot and shot and kept the pressure upon Sharapova the entire way. "It's frustrating because you work so hard to get to a certain point," she said. "You always want to get better. I feel like I've had a good enough summer. "I probably, definitely, could have performed better. But it's just not the way things go sometimes." Oudin, two weeks shy of her 18th birthday, was the crowd favorite, a role Sharapova has been accustomed to when playing at Flushing Meadows, but she knew the home-nation heroine would be the darling of the day as she has often been. "That's expected, considering she's an American, up-and-coming, obviously winning to get this far. So it's totally expected for the crowd to be with her," Sharpova said. "It's certainly not why I lost the match." Sharapova said the prodigy has enough court savvy to break through the wall the Russian usually raises during matches to avoid distactions. "I'm usually the type of player that concentrates on me," she said. "I certainly felt her presence because she was getting a lot of balls back and she made me hit a lot. She fought for it. She's a competitor. "But did that lose me the match? Absolutely not."