Unseeded Roberta Vinci, a 300-1 longshot entering the U.S. Open, 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 won the match 2-6, 6-4, 6-4 over Williams, who had won four straight Grand Slams and the last three U.S. Opens. It now belongs as one of the greatest upsets in sports history.