Greg Rusedski has put aside his off-court troubles to beat Argentina's Juan Ignacio Chela 7-6, 7-6 at the Sydney international.
The British number two regained his composure after failing to serve out for the match in the second set, winning a second successive tiebreak to send the higher-ranked South American tumbling out of the tournament on Monday.
Chela, a finalist in Sydney two years ago, twice had a chance to square the match at one set all only to be denied by the booming left-hand serve of Rusedski, who celebrated his victory by punching the air in delight.
"It meant a lot to me today," said Rusedski, who has vowed to clear his name after testing positive for the banned anabolic steroid nandrolone.
"This has given me a real lift, to come out and play this well and to be able to my job properly."
Rusedski was joined in the second round by Australia's Lleyton Hewitt, the former world number one and two-time Sydney champion, who defeated Sargis Sargsian of Armenia 6-4, 6-2.
Hewitt restricted himself to helping Australia win the Davis Cup after being eliminated in the quarter-finals at last year's U.S. Open.
He made his comeback at the Hopman Cup mixed team's event in Perth last weekend and says he is feeling revitalised after his lay-off.
"I'm feeling like I'm hitting the ball just as well [as ever]," Hewitt said.
"I've had a different preparation this year. I did a lot of hard work and training so that I'd last right through the Australian summer."
The tournament lost its first big name when Chile's sixth-seed Nicolas Massu fell 7-6, 2-6, 6-4 to Sydney teenager Todd Reid, who had claimed the scalp of Wayne Ferreira in Adelaide a week ago.
There were no major surprises in the first three women's matches played on Monday with Spain's Conchita Martinez, Italy's Francesca Schiavone and American Meghann Shaughnessy all recording wins.
Eight of the top-10 ranked women in the world have entered the event, one of the main lead-ups to the Australian Open, but the top four seeds were all handed first-round byes.