In one of the biggest upsets in tennis history, the unseeded Vinci beat Williams 2-6, 6-4, 6-4, ending the 33-year-old American's quest to become the first player since Steffi Graf in 1988 to win all four Grand Slam tournaments in a single season.
"It is an incredible moment for me. It's amazing. It's like a dream", said 43-ranked Vinci after her victory. "I think it's the best moment of my life."
Until this tournament, 32-year-old had not gone made it further than the quarterfinals in any major, reaching that far the 2012 and 2013 U.S. Open.
In another upset Friday, the 26-seeded Flavia Pennetta defeated No. 2-ranked Simona Halep 6-1, 6-3 to reach her first major final.
"I didn't think to be so far in the tournament", 33-year-old Pennetta said following the match. "I don't know how to handle all the pressure I have, but I think I played really well."
It will be the first time two Italian women will meet in a Grand Slam final since the Open era began in 1968.
