Jordan Thompson has become the first Australian to exit Wimbledon, going down 6-2 6-4 6-3 to Sam Querrey.
The 11th-seeded American, a semi-finalist last year, cruised to victory on a roasting hot opening day at the All England Club.
The defeat caps off a frustrating grass-court season for Thompson, who has failed to reach the heights of 12 months ago where he knocked out then-world No.1 Andy Murray from Queen's.
Thompson has now exited in the first round of all three grand slams this year and fallen out of the top 100, so may have to qualify for next month's US Open.
Big-serving Querrey hurled down 15 aces and returned well against the 24-year-old from Sydney who struggled to contain the Californian's powerful forehand.
The 30-year-old world No.13 took the first set in just 21 minutes after breaking Thompson in the third game of the match.
Querrey did the same in the opening game of the second set and after Thompson saved four break points in the first game of the third he got the vital breakthrough in the fifth.
Thompson had a golden opportunity to break back at 4-3 but was long with an overhead smash with the court at his mercy and Querrey made the most of his reprieve to close out the win.
Four other Australians are in action on Monday with Jason Kubler making his Wimbledon main-draw debut against Argentina's Guido Pella.
Qualifier John-Patrick Smith faces experienced Italian Andreas Seppi and John Millman meets Italy's Stefano Travaglia.
In the women's draw, Alja Tomljanovic faces American 10th seed Madison Keys.