Top seed Serena Williams eased into the third round of the Sony Open in Miami after claiming a crushing 6-1 6-1 victory over Flavia Pennetta.
Williams broke her opponent five times in the contest, although she was forced to save seven break points on her own serve.
Elswhere in the second round, world No 4 Agnieszka Radwanska opened her title defence with a comfortable straight sets win over Hsieh Su-wei.
Poland's Radwanska took a 6-3 6-2 victory over her Taiwanese opponent as she bids to defend the title she won last year by beating Maria Sharapova in the final.
Radwanska, a winner in Auckland and Sydney this year, broke her opponent four times in a match which lasted 65 minutes.
"I am very happy to have a quick match. The first match is always a little bit tough and tricky, especially coming from Indian Wells, where we have a little bit different conditions," she told the tournament's official website.
China's fifth seed Li Na made a successful return from a seven-week injury absence with a 6-3 6-1 victory over Kiki Bertens.
Former Wimbledon champion Petra Kvitova did not have things so easy as she was forced to come back from a set down to beat Peng Shuai 5-7 6-2 6-2. Ninth seed Caroline Wozniacki was also made to work for a 5-7 6-3 6-3 win over Karolina Pliskova.
Tenth seed Marion Bartoli was eliminated, however, as she retired when 6-3 4-1 down to Andrea Petkovic.
There was an upset win for wild card Ajla Tomljanovic of Croatia as she beat Germany's 24th seed Julia Goerges 7-6 (7- 4) 6-2. No 23 seed Anastasia Pavlyuchenkova also bowed out as she lost 4-6 6-2 6-2 to Garbine Muguruza Blanco.