The 36-year-old Williams is back in a Grand Slam final for the first time since Wimbledon in 2009 and her first here since 2003, when she lost to her younger sister, Serena.
She could get a chance to avenge that loss — 22-time major winner Serena Williams was playing 34-year-old Mirjana Lucic-Baroni later Thursday for a spot in the final.
“It means so much, mostly because she played so well. I mean, she played so unbelievable,” Williams said of the 25-year-old Vandeweghe, who was playing her first major semifinal. “To be able to get through the final from a match like this — I’m excited about American tennis as well.”
Williams needed four match points on Vandeweghe’s serve in the last game before converting. Then she put both hands on her face, almost in surprise.
“It’s more than a cherry on top,” she said. “It’s more than I dreamed of.”
Earlier, Bob and Mike Bryan earned a shot at a seventh Australian Open doubles title after a rain-interrupted 7-6 (7-1) 6-3 semifinal win Friday over Pablo Carreno Busta and Guillermo Garcia-Lopez.