Thanasi Kokkinakis has pushed highly-rated Italian Jannik Sinner but missed his moments in a straight sets exit in Adelaide.
The local favourite, a semi-finalist in the corresponding tournament last year, lost 7-6 (7-2) 6-4 to the world No.15 as a quarter-final berth went begging.
But the 21-year-old, coached by Australian Darren Cahill, took his chances to subdue the crowd and set up a final-eight showdown with Sebastian Korda.
Kokkinakis won just one of seven break points against the Italian.
Sinner won two of this three, twice breaking Kokkinakis's serve when the Australian appeared set to comfortably hold.
The Italian was off his game early thanks to the low afternoon sun that drenched the Memorial Park hard court, seven unforced errors in the first five games creating some momentum for Kokkinakis.
He was unable to convert that though, Sinner enjoying some luck when the ball bounced favourably off the net for a winner on one break point.
Kokkinakis only broke the Italian after he had lost his own serve, then missed two more break points at 5-5 in the first set.
Sinner rescued himself there, then cruised in the tie-break before drilling his powerful forehand to both corners early in the second set to land the decisive break of serve.
"It's tough to play against him, the last meeting was in Cincinnati and was a thriller (Sinner won in three tight sets)," Sinner said.
"It was a tough match; especially in the beginning with the sun and shadow, there wasn't a lot of rhythm.
"But after that and especially in the tie-breaker I raised my level."
Kokkinakis will remain in South Australia to defend his memorable Adelaide International 2 title next week, while he'll also look to gain valuable ranking points at Melbourne Park after a first-round exit last year.