Serena Williams upset by Roberta Vinci in U.S. Open semifinals

Roberta Vinci upset Serena Williams in the U.S. Open women’s semifinals on Friday at Arthur Ashe Stadium.

Roberta Vinci upset No. 1 Serena Williams in three sets in the U.S. Open women’s semifinals on Friday, ending Williams's hopes of completing the calendar Grand Slam. 

Vinci, who is unseeded, won Friday’s match 2-6, 6-4, 6-4 over Williams, who has won the last three U.S. Opens. Entering Friday, Williams had never dropped a set against Vinci. 

“I thought [Vinci] played the best tennis in her career,” Williams said. “She's 33 and she's going for it at a late age. So that's good for her to keep going for it and playing so well. Actually, I guess it's inspiring.”

Williams has won four straight Grand Slams. Had she won this year's U.S. Open, she would have become the first player since Steffi Graf in 1988 to complete the calendar Grand Slam. 

Williams has 21 Grand Slam titles, one behind Graf for the highest total in the professional era.

Vinci will face fellow Italian FlaviaPennetta in the final at 3 p.m. ET on Saturday after the tournament’s No. 26 seed upset No. 2 Simona Halep 6–1, 6–3 on Friday.

- Mike Fiammetta