NEW YORK (AFP) - Serena Williams saw her dream of a calendar year Grand Slam title sweep destroyed on Friday as Italy's Roberta Vinci shocked the world No. 1 to reach the US Open final against compatriot Flavia Pennetta.
Vinci battled back to stun the three-time defending champion 2-6, 6-4, 6-4, ending Williams' 33-match US Open win streak and 27-match Grand Slam win streak.
In Saturday's final, Vinci will face 26th-ranked compatriot Pennetta - who upset Romania's second-ranked Simona Halep 6-1, 6-3 - in the first all-Italian Grand Slam women's final in the Open Era.
"I think she played out of her mind. I don't think I played that bad. I think she just played really well," said Williams. "She played the best tennis of her career."
It was a shocking end to Williams' run at not only a sweep of the year's four major titles, a feat that hasn't been done since Steffi Graf's 1988 effort, but her bid for a 22nd Grand Slam title to match Graf's Open Era career record and a fifth Slam crown in a row.
"I don't want to talk about how disappointing it is for me," said Williams in a brief post-match news conference.
"I don't feel pressure. I never felt pressure. I never felt that pressure to win here. I said that from the beginning."
Vinci was overjoyed by her shock win.
"It's an incredible moment for me," Vinci said. "It's like a dream. I'm in the final. I beat Serena. It's an amazing moment. It's incredible.
"It's I think the best moment of my life."
Vinci apologised to the crowd for ending Williams' Grand Slam sweep dream.
"Sorry for the American people, for Serena, for the Grand Slam and everything. Today is my day. Sorry guys."
Vinci said she never expected to win after losing four prior matches against Williams without taking a set.
"No, really, it's true," she said. "When I wake up, I say, 'I have a semi final today. I play Serena. Try to enjoy.' I didn't expect that I win."
In the matchup of first-time Slam finalists, Vinci has a 4-5 career mark against Pennetta, who took just 59 minutes to dispatch Halep.
"It's amazing," Pennetta said. "I didn't think to be so far in the tournament. I played really well. I tried to play every match the best I can from the first one, don't worry about the draw and focus on the things I have to do on the court. And here I am."
Williams broke Vinci three times in taking the first set after only 31 minutes.
"I was serving and thinking, 'Oooh, it's impossible," Vinci said.
Williams fell behind triple break point in the first game of the second set but rescued them all to hold. Vinci reached triple break point again in the fifth game and Williams, after saving two with her ninth and 10th aces of the match, fired a backhand wide to surrender the break and a 3-2 lead.
Vinci held from there to force a third set, saving a break point with a net cord winner in the final game.
Williams smashed a backhand winner to break Vinci for a 2-0 lead in the third set but double faulted away a break to Vinci in the next game.
Williams fell behind in the fifth game and began emotionally yelling to herself as she held.
In the seventh game, Williams double faulted twice to fall behind, later missed a chance to hold when Vinci hit a winner and urged a huge roar from the crown, and in the end swatted a forehand long to hand Vinci a break and a 4-3 lead.
Williams had two break points on Vinci in the eighth game but sent forehands long and wide and a backhand return wide to hand Vinci a 5-3 lead. Williams held but could not threaten Vinci in the last game, falling after two hours on the Italian's forehand drop volley winner.
