Seven-time Grand Slam champion Venus Williams became the oldest semi-finalist in US Open history at age 37 on Tuesday by defeating two-time Wimbledon champion Petra Kvitova 6-3, 3-6, 7-6 (7/2).
US ninth seed Williams, seeking her third US Open crown, advanced to a Thursday matchup against 83rd-ranked compatriot Sloane Stephens for a spot in Saturday's final.
"I'm so fortunate to have won that match. It came down to the wire," Williams said. "I try to tell myself enjoy the competition, enjoy the battle and I think I was able to do that."
Williams, who improved to 2-4 all-time against the Czech 13th seed, will return to the world top five for the first time since January 2011, a span that saw her diagnosed with the energy-sapping disease Sjogren's Syndrome.
Williams, the oldest Slam semi-finalist since Martina Navratilova at Wimbledon in 1994, won the 2000 and 2001 US crowns.
She was runner-up this year at Wimbledon and the Australian Open and could reach three Slam finals in a year for the first time since 2002.
If Americans Madison Keys and CoCo Vanderweghe win Wednesday, they will produce the first all-American US Open semi-finals since 1981.
"That would be huge," Williams said. "I'd love that."