Li Na celebrates match point against Kiki Bertens during their second-round match at the Sony Open at Crandon Park Tennis Center on Thursday in Key Biscayne, Florida. [Clive Brunskill / Agence France-Presse]

China's Li Na made a winning return to WTA action on Thursday, beating Kiki Bertens of the Netherlands 6-3, 6-1 in her second-round opener at the Miami WTA and ATP Masters hard-court tournament.

Li had been sidelined for seven weeks after hurting her left ankle in the final of the Australian Open, where she fell to Victoria Azarenka.

"I wasn't nervous today before the match, but I was excited," Li said. "For the last six or seven weeks I haven't played any tournaments so I was happy with the result and to win my first match after such a long time."

Li, ranked fifth in the world and seeded fifth in a field headed by world No 1 Serena Williams, didn't drop her serve, saving both break points she faced in the emphatic 67-minute match.

She was buoyed by a vocal contingent of fans, something she wasn't expecting.

"There were a lot of fans there to support me today, I was like 'Wow!'" she said. "My game was pretty good. I followed the plan of what I should do. I just had to believe in myself that I could do it."

Williams also got her quest for a record sixth WTA title on the hard courts of Miami off to a brisk start with a 6-1, 6-1 victory over Italian Flavia Pennetta.

"I think I missed a few shots, but only because I think I was off footwork-wise," Williams said. "But it's always just good to win a match and stay in the tournament and keep going."