British number one Kyle Edmund was on the wrong end of an upset in Brisbane as he crashed out to qualifier Yasutaka Uchiyama in straight sets.
Edmund, third seed at the hard court tournament, nearly went a break up in the fifth game of the first set but his Japanese opponent saved two break points.
The remainder of the set also followed serve.
Edmund broke twice during the tiebreak but failed to convert two set points and Uchiyama, ranked 185 in the world, won four points in a row to take the set in just under an hour.
Uchiyama wrapped up the second set in 36 minutes, claiming a spot in the next round after converting his second match point.
The damage was done in the third game, where Edmund was broken to love as Uchiyama took the match 7-6 (8/6) 6-4.
Dart misses the bullseye
Harriet Dart lasted less than an hour as she went down 6-2 6-0 to Latvian Anastasija Sevastova at the Brisbane International.
Briton Dart, 22, lost two consecutive service games in the first set to the world number 11 and won only 12 points in the final set.
Eighth seed Sevastova, who will go on to play Naomi Osaka in the next round, converted on her fourth match point.
At the same tournament, world number seven and fourth seed Petra Kvitova suffered a straight-sets defeat to Estonia's Anett Kontaveit 7-5 7-6 (1).
A break in the 11th game of the first set was enough for the world number 20 to draw first blood, while four breaks of serve in the second set saw it finish 6-6.
Kvitova was broken four times, the last as her opponent had match point.
At the ASB Classic in Auckland, top seeded 2017 WTA Tour finals winner Caroline Wozniacki beat Laura Siegemund of Germany 6-3 6-2 and number three seed Su-Wei Hsieh saw off Monica Puig 6-1 7-6 (3).