Roberta Vinci of Italy and Serena Williams of the United States prior to their Women’s Singles Semifinals match at the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 11, 2015 in the Flushing neighborhood of the Queens borough of New York City

*Unseeded Roberta Vinci has beaten Serena Williams at the U.S. Open semifinals, ending Serena’s Gland Slam bid and causing Vinci to apologize to the crowd.

“I’m sorry,” she said in her post-game interview, before going on to say she was proud of herself for persevering.

The 43rd-ranked Italian won 2-6, 6-4, 6-4.

Per AP:

Vinci had never won a set off the 21-time major champion in four previous meetings and was in her first career Grand Slam semifinal at age 32.

So tense she was guiding in overheads, Williams became more and more frustrated by Vinci’s defense and creative shot-making in the final two sets. She had won in three sets 11 times in majors this year in her pursuit of the first Grand Slam since Steffi Graf in 1988, but was unable to dig out of this hole.

Williams was on the verge of becoming the first woman to win all four majors in a season since Steffi Graf in 1988. Williams also could have tied Graf for the second-most Grand Slam singles titles behind Margaret Court’s 24.

Vinci will face countrywoman, 26th ranked Flavia Pennetta, who defeated No. 2 seed Simona Halep earlier Friday, in the U.S. Open final.