Veteran Kimiko Date-Krumm provided a first-round shock at the Bank of the West Classic by coming from a set down to beat Sabine Lisicki.
The 44-year-old lost the first set to an opponent 18 years her junior and when the 2013 Wimbledon finalist also stormed 4-1 up in the second, the match looked set for a swift conclusion.
But Date-Krumm, now ranked down at 173 in the world to her opponent's 24th spot, produced a stunning comeback to level the set, win it on a tie-break and then complete a 1-6 7-6 (7/4) 6-2 win.
Both seeds in action in Stanford came through, though Elina Svitolina needed two and a half hours to see off fellow Ukrainian Kateryna Bondarenko 4-6 6-4 7-5.
Germany's Angelique Kerber, seeded three places higher than Svitolina at number five, had an easier time of things as she beat Russia's Daria Gavrilova 6-1 6-3.
American Varvara Lepchenko beat Croatia's Mirjana Lucic-Baroni 3-6 6-2 7-6 (7/4) to set up a second-round clash with top seed Caroline Wozniacki.
Ajla Tomljanovic lost the first set to Vitalia Datchenko but launched an emphatic comeback to win 3-6 6-0 6-0. F ellow Croatian Ana Konjuh beat Saisai Zheng of China 6-3 6-4.
Source: PA
