World number two Serena Williams suffered a shock defeat in her second match back after injury at the ASB Classic in New Zealand.
The 35-year-old lost 4-6 7-6 (7-3) 4-6 to compatriot and world number 72 Madison Brengle in Auckland.
Williams had returned to action after four months out on Tuesday, claiming she was 'rusty' despite winning.
It was a disappointing day for the Williams sisters after older sister Venus withdrew with an arm injury.
The 36-year-old beat New Zealand wildcard Jade Lewis 7-6 (7-2) 6-2 and was due to play Japan's Naomi Osaka in the second round later on Wednesday but pulled out before the match.