British number one Kyle Edmund suffered a shock defeat by Japan's world number 185 Yasutaka Uchiyama in the second round of the Brisbane International.
Edmund, the world number 14 and third seed, lost 7-6 (8-6) 6-4 to the qualifier.
The Briton, who had a bye in the first round, failed to convert two set points in the opening set.
He was broken to love in the third game of the second set and Uchiyama went on to wrap it up quickly.
Britain's former world number one Andy Murray, playing in his first tournament since September, will be in action later on Wednesday when he faces Russian fourth seed Daniil Medvedev.