Fifth seed Alexander Bublik was a first-round casualty at the Auckland Classic on Monday, ousted in straight sets by David Goffin in a surprise one week out from the Australian Open.
Big-serving Kazakh Bublik was expected to go deep in a tournament that has attracted a relatively lightweight field to New Zealand.
However, the world number 36 was beaten 6-3, 6-4 by experienced Belgian Goffin, who adeptly handled a barrage of thunderbolt serves, breaking serve on six occasions.
"His first serve is just amazing – like 220 (kmh) all the time and close to the line, so it's not easy to return," Goffin said.
"He started to hit the ball really well in the second set and he's very dangerous when he's relaxed."
Goffin, 32, surprised himself with the quality of his performance.
It came on the back of losses to Grigor Dimitrov and Stefanos Tsitsipas when Belgium bowed out early at the United Cup last week.
The evergreen Richard Gasquet won his Auckland opener in straight sets, along with French compatriot Constant Lestienne.
American Jenson Brooksby needed three sets to beat Italian Fabio Fognini.
Top seed Casper Ruud of Norway gets to skip the first round with a bye, along with Briton Cameron Norrie and Argentine pair Diego Schwartzman and Francisco Cerundolo.