World number two Roger Federer and number three Novak Djokovic eased into the third round of the Miami ATP Masters 1000 tournament with victories over qualifiers.
Switzerland's Federer, playing just his second tournament since losing to Rafael Nadal in the final of the Australian Open, beat American Kevin Kim 6-3, 6-2.
Federer said it was always tricky taking on an unfamiliar opponent, even one ranked well below him.
"I've never played him before, so of course I was always going to get surprised in some points just because I didn't know what his favorite shot was," he said.
"But I realized very quickly what his pattern was, especially on the serve, as well. Even though he had a good serve today, he had a good few games, but I think I did well today. It was a great start to the tournament."
The 13-time Grand Slam champion next faces Germany's Nicolas Kiefer, a 5-7, 7-6 (7/5), 6-2 over France's Fabrice Santoro.
Djokovic booked his third-round berth with a 6-3, 6-2 victory over Canadian Frank Dancevic 6-3, 6-2.
Serbia's Djokovic saved all six break points he faced, breaking Dancevic three times en route to a victory in 70 minutes.