Serena Williams has fallen to a shock defeat at the Auckland Classic, losing her second-round match to fellow American Madison Brengle 6-4 6-7 (3-7) 6-4.
The top seed and world No.2 struggled with her timing in the windy conditions in Auckland and faced a dogged opponent who kept returning the ball.
Williams saved three match points, but then double-faulted to hand world No.72 Brengle a huge victory after two hours and 13 minutes on court.