Lleyton Hewitt began his summer hard-court campaign with victory over US wildcard Donald Young at the Legg Mason Tennis Classic in Washington DC.
Hewitt, contesting his first tournament since losing to Andy Roddick in the Wimbledon quarter-finals, reached round two with a 7-5 6-2 win.
Russia's Mikhail Youzhny required three sets to overcome Robert Kendrick, eventually prevailing 7-5 3-6 6-1.
Philipp Petzschner came from behind to beat Teimuraz Gabashvili 4-6 6-3 6-4.
Former world number one Hewitt, 28, the 2004 champion in Washington, said: "It's always hard after a few weeks off, so it's nice to get through in straight sets."
Top seed Andy Roddick, a three-times winner of the event, will play either fellow American Robby Ginepri or Benjamin Becker of Germany in his first match on Wednesday.
Meanwhile, British number two Alex Bogdanovic enjoyed a morale-boosting win in round one of the Odlum Brown Van Open in Vancouver.
The 25-year-old left-hander beat Dutch qualifier Igor Sijsling 6-2 5-7 7-5 to set up a second-round meeting with American Scoville Jenkins.