US Open 2015: Serena Williams beaten in semi-finals by Roberta Vinci - ending hope of calendar year grand slam

Williams suffers defeat at the penultimate hurdle to her 'Serena Slam' hopes

Serena Williams of the US chases down but misses a return to Roberta Vinci (AFP)

Serena Williams' attempt to become only the fourth woman to win a calendar-year Grand Slam ended in extraordinary fashion at the US Open. In one of the greatest shocks in the sport’s history, the world No 1 was beaten 2-6, 6-4, 6-4 by Roberta Vinci, the world No 43, who had failed to take a set off Williams in all four of their previous meetings.

Against all the odds, Saturday’s final will be contested by two Italians after Flavia Pennetta, the world No 26, beat the world No 2, Simona Halep, 6-1, 6-3. Vinci and Pennetta will be playing in their first Grand Slam finals at the ages of 32 and 33 respectively. It will be the first all-Italian Grand Slam final in the Open era, with Pennetta the oldest player to make her final debut.

Williams, who had completed her second “Serena Slam” (winning all four Grand Slam titles in a row but not in the same calendar year) at Wimbledon, was just two victories away from joining Maureen Connolly, Margaret Court and Steffi Graf as the only women to win a pure Grand Slam.

When she won 21 of the last 29 points to take the first set the 33-year-old American appeared to be coasting, but from the second set onwards she looked increasingly tense, while Vinci grew in confidence. The Italian played a clever game, varying the pace of her shots, pulling Williams into the net and repeatedly forcing her to play the extra ball.

Roberta Vinci of Italy reacts after defeating Serena Williams

At the end of the second set Williams was given a warning after smashing her racket in anger. She went 2-0 up in the decider, but Vinci broke back immediately and made a decisive second break in the seventh game, during which she cocked her ear to the crowd like a footballer demanding the recognition of home fans. The Italian kept her nerve when she served out to love for the match, winning two of the points with beautifully judged half-volleys.

Williams insisted she had not buckled under the weight of expectation . “I never felt pressure,” she said. “I never felt that pressure to win here. I made a couple of tight shots, but for me it’s normal in any match to make two tight shots. Other than that, I don’t think I was that tight.”

She said Vinci had played “literally out of her mind” and had never performed better. “I don’t think I played that bad,” Williams said. “I made more unforced errors than I normally would make, but I think she just played really well.”

Williams was asked how she would get over the defeat. “Anyone else want to ask a different question than that?” she said, preferring to reflect on the positives. “I felt very happy to get that win at Wimbledon. I did win three Grand Slams this year. I won four in a row. It’s pretty good.”

Vinci described it as the best moment of her life. “It’s an incredible moment for me,” she said. “It’s amazing. It’s like a dream. I’m in the final. I beat Serena. When I woke up this morning I said to myself: ‘OK. I have a semi-final today. Enjoy it. Don’t think about Serena.’ I didn’t expect to win.”

Pennetta brushed aside Halep in just 59 minutes. The world No 2, attempting to become the first Romanian to reach the final here in the Open era, played a wretched match and said afterwards that she had felt flat and low on energy. Pennetta, who lost to Victoria Azarenka in her only previous Grand Slam semi-final appearance here two years ago, trailed 3-1 in the second set but then made her decisive move by winning 15 points in a row.

The men’s semi-finals – Novak Djokovic against Marin Cilic and Roger Federer against Stan Wawrinka – were scheduled for later in the day.