The Grand Slam will have to wait.
Two victories from joining the most prestigious club in tennis, Serena Williams ran into a roadblock at the United States Open.
In one of the biggest surprises in tennis history, Roberta Vinci, an unseeded Italian veteran playing in her first Grand Slam semifinal, defeated Williams, 2-6, 6-4, 6-4, on Friday.
“It’s an incredible moment for me,” said Vinci, who cried in her chair after the upset and called the victory the “best moment of my life.”
Instead of Wiliams playing for a Grand Slam in Saturday’s final, it will be an all-Italian final between Vinci and the 26th-seeded Flavia Pennetta.
In another upset earlier in the day, the 26th-seeded Pennetta defeated No. 2 Simona Halep, 6-1, 6-3. But that, in relative terms, was no surprise compared to what Vinci engineered later in the afternoon on Arthur Ashe Stadium.
Williams was attempting to become the first player since Steffi Graf in 1988 to complete a Grand Slam, winning the Australian Open, the French Open, Wimbledon and the U.S. Open in the same year.
Williams had never even lost a set to Vinci in four previous meetings.
She came into Friday with a 33-match winning streak at Grand Slam tournaments and had not lost at the U.S. Open since the 2011 final.
Pennetta, 33, and Vinci, 32, have each won Grand Slam titles in doubles, but neither had advanced to a Grand Slam singles final until Friday.
Vinci apologized to the crowd for changing the story line.
“For the American people, for Serena, for the Grand Slam and everything,” she said. “But today is my day. Sorry, guys.”