Big-serving Sam Groth has bowed out in the first round of the Brisbane International on Monday night, beaten 7-6(8), 6-4 by South Korean teenager Hyeon Chung on Pat Rafter Arena.
World No.51 Chung booked a second-round clash with third seed Marin Cilic after seeing off the reigning Newcombe Medallist.
Earlier Aussie wildcards Ben Mitchell and John-Patrick Smith also fell at the first hurdle.
The remaining Aussie men – Bernard Tomic, wildcard James Duckworth and qualifier Oliver Anderson – feature in first-round action on Tuesday.
READ: Dimitrov needs 6mp to hold off Simon
Davis Cup regular Groth appeared in complete control against the bespectacled 19-year-old when he led the first set 5-2. But Chung showed why he was voted last year’s ATP World Tour most improved player by finding a way to blunt Groth’s serve, which pushed 230km/h.
World No.60 Groth made 26 unforced errors as his first set unravelled. He came back from 4-1 down in the second but Chung closed out the match against the shellshocked local.
Groth had hoped to at least match his 2015 Brisbane performance when he downed defending champion Lleyton Hewitt on the way to the quarterfinals.
The 28-year-old – holder of the world record for the fastest serve at 263km/h – went on to have a breakthrough 2015.
He received the Newcombe Medal after helping Australia reach the Davis Cup semi-finals and reached the third round of a major for the first time at the Australian Open and then again at Wimbledon.
Earlier, German qualifier Tobias Kamke booked a second-round clash with defending champion Roger Federer by downing Queenslander Mitchell 6-2, 6-4. Smith fell 4-6, 6-3, 6-2 to American Denis Kudla.
Earlier, Bulgaria’s Grigor Dimitrov upset fifth-seeded Frenchman Gilles Simon in the first round. The 2014 Australian Open quarter-finalist, whose pop star girlfriend Nicole Scherzinger watched from the stands, will next meet the winner between American Steve Johnson and Serbia’s Viktor Troicki.