Delray Beach, USA, 29 February 2012 | AAP

Bernard Tomic has won his first ATP Tour match since reaching the fourth round of last month’s Australian Open.

Tomic beat German veteran Tommy Haas 6-4 6-3 in the opening round of the Delray Beach International on Wednesday.

Australia’s eighth seed next faces American qualifier Tim Smyczek for a place in the quarter-finals of the $US500,000 ($A465,000) hardcourt event.

Smyczek defeated Austrian Jurgen Melzer 6-4 2-6 7-5 in his opener.

Fellow Australian Marinko Matosevic upset big-serving Croat Ivo Karlovic 6-3 6-4 to join Tomic in the second round.

Matosevic will play US sixth seed Alex Bogomolov, who downed countryman Michael Yani 6-3 6-1.

Other first-round winners on Wednesday included top seed John Isner, who beat fellow American Jesse Levine 6-4 7-6(15).

Finn Jarkko Nieminen ousted Croatian second seed Marin Cilic 6-3 3-6 6-2 and Belgian Steve Darcis eliminated Serbian third seed Viktor Troicki 6-4 4-6 6-4.