Serena Williams was sent crashing out of the WTA San Jose tournament on Tuesday, losing 12 straight games in a shocking first-round defeat to unseeded Johanna Konta.
Williams, who was playing her first match since dropping the Wimbledon final, is trying to regain her top form after missing most of the 2017 season due to a pregnancy.
But the 23-time Grand Slam winner struggled mightily against the British No. 1 and former winner Konta, who crushed Williams 6-1, 6-0 in just 51 minutes on the main Stadium.
Williams, who was seeded sixth, managed just nine winners against 25 unforced errors and had her serve broken six times.
While in the mens tennis, Three-time Grand Slam champion Stan Wawrinka, struggling in his comeback from left knee surgery, was ousted in the first round by US qualifier Donald Young at the ATP and WTA Washington Open on Tuesday.
Young, ranked 234th, outlasted the 33-year-old Swiss 6-4, 6-7 (5/7), 7-6 (7/3) and advanced to a second-round match with Japanese seventh seed Kei Nishikori.
Wawrinka, ranked 198th, fell to 6-11 this year after missing most of nine months before returning in May.