Ukraine's third-seeded Alexandr Dolgopolov and Croatian fourth seed Ivo Karlovic advanced to the second round of the ATP Delray Beach Open with victories.
Alexandr Dolgopolov of the Ukraine hits a backhand return in the final of the Kooyong Classic tennis event in Melbourne on January 16, 2015
Dolgopolov fired nine aces and dropped his serve only once in defeating Russia's Teymuraz Gabashvili 7-6 (7/4), 6-3 while Karlovic blasted 23 aces to oust Germany's Dustin Brown 6-3, 6-7 (3/7), 6-2.
Next up for Karlovic will be either Australia's Thanasi Kokkinakis or Serbian Filip Krajinovic while Dolgopolov has a round-of-16 date with an American, either Tim Smyczek or Stefan Kozlov.
"I think I did quite well," Dolgopolov said. "I was not my best in the first set, so winning that was really important and the second set was much better.
World number 24 Dolgopolov is bidding to win his third title, having captured the 2012 Washington Open and the 2011 Croatian Open.
The 26-year-old right-hander last reached a final one year ago this week, losing to Spanish superstar Rafael Nadal in Rio de Janeiro.
"I'm just going to go match by match," Dolgopolov said. "I know I am ranked quite high but that doesn't mean I am in top shape. If you think about going deep, you (aren't focused) on every match."
Karlovic never faced a break point in outlasting Brown, who had beaten him in both prior meetings, which came last year at Doha and Munich.
Brown, ranked 68 spots below Karlovic at 97th in the world, surrendered a break in the final game to fall after one hour and 41 minutes.
Also reaching the second round was US wildcard Denis Kudla, who eliminated Slovakian Lukas Lacko 6-3, 6-4. Kudla will next face either US qualifier Eric Quigley or French fifth seed Adrian Mannarino.
The top seed is South African Kevin Anderson, who lost to fifth-ranked Kei Nishikori in Sunday's Memphis final.
Anderson has lost his last six ATP finals, his most recent crown coming in 2012 at Delray Beach, where he now resides.