Roddick's easy win capped a day in which former NCAA champion Amer Delic upset No. 7 seed Carlos Moya, 6-2, 6-7 (5), 7-6 (5); 19-year-old Argentine Juam Martin del Potro, the third seed, beat Italian qualifier Andrea Stoppini, 6-4, 6-2; and March Gicquel of France beat 19-year-old American Donald Young, 6-3, 6-3.
Roddick, who had withdrawn from last week's tournament at Cincinnati with neck and shoulder problems, said he had no problems in either area during the 73-minute match. He said it was a good way to return, even though Vemic's style made it hard for Roddick to assess his own game.
"He plays a little wild with the drops and slices," Roddick said. "I wasn't expecting a lot of rhythm and I don't think I got much. It's a good strategy for him, but it's tough to actually win a match like that. To be able to get through rather straightforward was a good thing."
Delic, a 6-foot-5 right-hander, who is playing in his fifth ATP Tour event of the year, served well in the 2-hour, 18-minute match, hitting 14 aces and saving four break points while capitalizing on all four chances to break Moya. The 31-year-old Moya had reached the quarterfinals at Cincinnati last week.
Delic took control of the third-set tiebreaker by capturing six points in a row after Moya took a 3-0 lead and won it when Moya hit a backhand long on the second match point.
"I lose six points in a row. That never happens," Moya said with a shrug. "I got a little bit nervous and he played well on those points. He went for big shots and they worked for him. I got a little bit tired.
"It took awhile for me to get into the match. My legs were heavy. He served very well and I wasn't moving well."
The win, Delic's sixth in 10 tour matches this year, moves him into Friday's quarterfinals against del Potro.
It is far different than last year, when Michael Berrer beat Delic in the first round here to start a streak of 10 straight opening round losses for the 137th-ranked Florida resident who led Illinois to the 2003 NCAA team and individual championships.
Young, who had what he said was the best win of his career on Tuesday when he ousted two-time event champion and No. 8 seed Tommy Haas, couldn't sustain that level of play. He hasn't won back-to-back matches on the tour since advancing to the third round at Indian Wells in mid-March.
"He played well, but I don't think I played the way I wanted to play," said Young, who lost the final three games of the match. "I had my best win and I couldn't play at the same level.
"That's something I have to change. I don't think it's a matter of the shots or the strategy, I think it's the mental part of it, playing at the same level, playing consistently."
Gicquel, who beat American wild card Zack Fleishman in the first round, said Young has a lot of talent, but needs to improve his footwork.
"I was playing good today," Gicquel said. "It's always hard playing an American when you're in the USA, so I just tried to focus on the whole match. I like the atmosphere here and the people."