(CNN) -- Second seed Dinara Safina of Russia came safely through her first test in the WTA Tour event at Key Biscayne with a straight sets win over Mathilde Johansson.
iIndian Wells runner-up was impressive with a straight sets second round victory in Florida.
Safina, who can claim the world number one spot with victory at the Sony Ericsson Open, won her second round match 6-1 6-3.
French Open champon and Indian Wells runner-up Ana Ivanovic also eased through with a 6-0 6-3 win over Ukrainian qualifier Mariya Koryttseva in a Friday night match.
World number one Serena Williams and sister Venus, who sat out last week's WTA event at Indian Wells, are in action on Saturday. Russian Vera Zvonarera, who beat Ivanovic to the title in California, also begins her campaign.
Other seeds to progress to the third round included Russians Elena Dementieva and Svetlana Kuznetsova, who both dropped sets.
Fourth seed Elena Dementieva dispatched wildcard Anastasia Pivovarova 6-0 3-6 6-3, while eighth-ranked Kuznetsova beat qualifier Tamira Paszek 2-6 7-5 6-1.
11th seed Victoria Azarenka of Belarus saw off fellow-Indian Wells semifinalist Anastasia Pavlyuchenkova 6-2 6-2 and 13th seed Caroline Wozniacki beat Australia's Jelena Dokic 6-3 5-7 6-2.
French veteran Amelie Mauresmo is also emerging as a challenger in the prestigious tournament which is being played alongside the men's Masters Series event.
She beat promising young Slovakian Magdalena Rybarikova 6-3 1-6 6-2 and told the official WTA Tour Web site that she was enjoying her tennis again.
"For a year or two I wasn't really having fun on the court; I'm finding this much more in 2009, so that's the goal, just to keep going for at least one more year really, to find the happiness of being on the court again. That's where I am right now."