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.
Tournament director Karl Budge said that the seven-time Grand Slam winner “wasn’t able to serve as she would like to and at the level that we have come to expect from Venus and unfortunately that has taken her away from the tournament this year”.
Venus later posted a message on Twitter thanking her supporters.
Britain’s Naomi Broady won her opening match at the tournament before suffering a second-round exit.
Broady, ranked 90 in the world, beat Danka Kovinic of Montenegro 7-6 (7-5) 6-3 to ensure she remains in the top 100.
The British number three, who reached the quarter-finals last year, was back on court later on Wednesday but lost 7-5 6-4 to Germany’s Julia Goerges, who is 37 places above her in the rankings.