French sixth seed Jo-Wilfried Tsonga and Chinese fifth seed Li Na advanced with straight-set triumphs on a hot and humid Saturday at the $8.5 million WTA and ATP Miami Masters hardcourt tournament.
Tsonga defeated Serbia's Viktor Troicki 7-6 (8/6), 6-3 to reach the third round while Li smacked 19 winners and fought off a late comeback bid to defeat American Varvara Lepchenko 6-2, 6-4 and reach the fourth round.
British second seed Andy Murray was set to face Australian Bernard Tomic while Czech fourth seed Tomas Berdych meets Spain's Daniel Gimeno-Traver in later men's second-round matches.
Later women's matches will send World No. 1 Serena Williams against Japan's Ayumi Morita and Venus Williams against fellow American Sloane Stephens.
Tsonga seized a 5-1 lead in the tie-breaker but the Serb scored the next five points to earn his second set point. Tsonga denied him with an ace and two points later, Troicki netted a drop volley to hand the Frenchman the first set.
Tsonga needed four break chances but finally took the opening game of the second set when Troicki netted a backhand.
Troicki went 0-for-5 on break chances in the second set, the last coming in the eighth game, as Tsonga held then broke again to claim the match and improve to 13-4 this year.
He will face either Finland's Jarkko Nieminen or Slovakian Martin Klizan in the next round.
Li had been sidelined for seven weeks after hurting her left ankle in the Australian Open final, which she lost to Victoria Azarenka, but she improved to 16-2 this season and booked a round-of-16 date with the winner of a later match between Danish ninth seed Caroline Wozniacki and Spain's Garbine Muguruza.
Lepchenko made 19 unforced errors in falling to 4-7 for the season.
Li dominated the opening set, dropping only five points on her serve while Lepchenko managed only one winner against 10 unforced errors.
Li jumped ahead 4-2 in the second set before Lepchenko managed her first break-point chance. The American took advantage with a net cord winner to break back and then held to level the set at 4-4.
After holding, Li ended matters in the 10th game. Lepchenko hit a backhand winner and Li netted a backhand attempt on the Chinese star's first two match points but Li smashed a forehand winner on her third match point for the victory.
On the men's side, French eighth seed Richard Gasquet dispatched Belgian Olivier Rochus 7-5, 6-2 to reach a third-round match against either Taiwan's Lu Yen-Hsun or Russia's Mikhail Youzhny.
US 17th seed Sam Querrey rallied to eliminate Poland's Lukasz Kubot 4-6, 6-3, 6-3 in one hour and 47 minutes. Querrey will next face either Canadian 14th seed Milos Raonic or Frenchman Guillaume Rufin.
Belgium's David Goffin ousted German 15th seed Philipp Kohlschreiber 7-6 (7/5), 4-6, 6-2. Next in Goffin's path will be the winner of a later match between Spanish 10th seed Nicolas Almagro and Argentina's Guido Pella.