Sydney, Australia, 7 January 2013 | AAP

Australian wildcard James Duckworth has let slip a golden opportunity to register the biggest win of his fledgling tennis career, going down in three tight sets to Uzbekistan’s Denis Istomin at the Sydney International on Monday.

The 209th-ranked Duckworth relinquished a break of serve after being up 2-0 in the deciding set, eventually going down 6-7(4) 6-4 7-6(3).

Istomin, ranked 43 in the world, had dumped Lleyton Hewitt from the first round of the Brisbane International last week before going down to eventual champion Andy Murray at the quarterfinal stage.

The big Uzbek looked on the ropes at various stages in the final set but the 20-year-old Duckworth couldn’t consolidate his early lead nor press through when he had other chances to snatch further breaks in the third set.

Things get considerably tougher for Istomin in the second round where he is slated to face fourth seed Fernando Verdasco.

Later in the day, Casey Dellacqua made a straight-set first-round exit at Sydney Olympic Park Tennis Centre.

Dellacqua lost 6-4 6-1 to 42-year-old Japanese qualifier Kimiko Date-Krumm, the world No.112 and oldest singles player on the WTA Tour.

Meanwhile, Matt Ebden was up a set and a break before being run down by Spanish eighth seed Marcel Granollers 5-7 7-5 6-1 on Ken Rosewall Arena.

World No.105 Ebden, who was up two sets to love against highly-rated Japanese Kei Nishikori at last year’s Australian Open before going down in five, looked the goods when up 4-2 in the second set.

But the 25 year-old’s game began to unravel after a botched smash when at deuce and 4-2 on his serve.

Granollers, world No.34, took full advantage to snatch the break back, in total claiming 11 of the last 13 games to claim the match, an apparent leg injury also hampering Ebden in the decider.