How Serena's Grand Slam bid was brought to a grinding halt

Inspired Vinci rallies to beat World No 1 and then tells US crowd: ‘But today is my day. Sorry guys’

Serena Williams's bid for a rare calendar-year Grand Slam came to a shocking halt at the US Open on Friday when the defending champion suffered one of the greatest tennis upsets to unseeded Italian Roberta Vinci.

The 32-year-old Vinci ended Williams's run of three straight US Open titles and her bid to become the fourth woman to sweep all four grand slam singles titles in the same year with a 2-6, 6-4, 6-4 win that stunned the Arthur Ashe Stadium crowd.

"I thought she played the best tennis in her career," Williams said about her 43rd-ranked opponent who was playing in her first grand slam singles semi-final.

"You know, she's going for it at a late age.

"Actually, I guess it's inspiring. I think she played literally out of her mind."

For world number one Williams, it marked the first time she lost to Vinci in five career meetings after a string of easy straight-set wins against her.

Vinci's extraordinary win set up an all-Italian women's final on Saturday against 33-year-old Flavia Pennetta, who routed second seed Simona Halep of Romania 6-1, 6-3.

"This is an incredible moment for me," Vinci said after taking a long moment to compose herself for the on-court interview.

"It's amazing. It's like a dream. I'm in the final. I beat Serena."

Vinci, a winner of five grand slam doubles titles, took advantage of some loose points from the American, who appeared to feel the pressure of her pursuit of tennis history.

Vinci played with extraordinary composure and used her net-play skills to advantage with an inspired performance.

Following a dominant first set from Williams, the Italian made a fifth-game service break stand up to force a third set as the heavily-favoured American racked up unforced errors as she tried to overpower her opponent.

Williams destroyed her racket with a frustrated smash before the start of the climactic set and tried to lift herself to victory with clenched-fist roars on winning points as the third set unfolded.

But the steady Italian refused to buckle.

Williams broke for an early 2-0 lead but Vinci broke right back when the top seed double-faulted.

The world number one, who hammered in 16 aces, double faulted twice in the seventh game when Vinci broke her again for a 4-3 lead in a game in which she celebrated a forehand volley winner by waving her arms for some appreciation from the crowd.

Three games later, the Italian coolly half-volleyed a winner to cap the extraordinary result.

"When I wake up today I say, 'OK, I have a semi-final today, try to enjoy. Don’t think about Serena. Play, enjoy. I did not expect that I won."

Vinci said the tension was palpable.

"At the end we had a lot of pressure, I think both (of us)," she said.

"In my mind I say, 'Put the ball on the court, don’t think. Try to put all the balls on the court. Don’t think about Serena in the other court. And run.' And then I won."

The beaming Vinci was almost apologetic about ending the single season Grand Slam run of Williams.

"Sorry guys," Vinci said.

"For the American people, for Serena, for the Grand Slam and everything. But today is my day. Sorry guys," said the Italian, who was showered with an Arthur Ashe ovation.