Serena Williams survived an "irresponsible" second set lapse on Friday to see off Sweden's Rebecca Peterson 6-3, 1-6, 6-1 in her second-round opener of the WTA and ATP Miami Open.

"I wasn't really happy with my performance," admitted the 23-time Grand Slam champion, who is playing in just her third tournament of 2019 having lost in the Australian Open quarter-finals before retiring in the second set of her third-round match against Garbine Muguruza with a viral illness at Indian Wells last week.