Five-time champion Serena Williams was knocked out in the quarterfinals of the Australian Open by back spasms and fellow American Sloane Stephens.
Williams, 31, who had trouble serving and moving on the court after wrenching her back in the second set, lost 3-6, 7-5, 6-4 to the 19-year-old Stephens.
Williams, who smashed her racket on the court in frustration early in the third set, had won 20 straight matches and two consecutive Grand Slam titles with her victories last year at Wimbledon and the U.S. Open.
Williams led the second set 2-0 before Stephens stormed back to take a 5-3 lead. In that eighth game of the second set, Williams hurt herself while rushing to the net to win a point.