Serena Williams' match was more than an hour old Monday before she began to make some noise.
''Come on!'' she shouted at her fist through gritted teeth, adding a soundtrack to her comeback. Her demeanor transformed, Williams rallied past Dominika Cibulkova in the fourth round of the Sony Open, 2-6, 6-4, 6-2.
The top-ranked Williams, seeking her sixth Key Biscayne title and her first since 2008, was down a service break trailing 4-1 in the second set before she swept the final five games of the set. She also won the last three games of the match and served it out at love with three aces.
Williams' opponent in the quarterfinals will be No. 5-seeded Li Na, who beat wild card Garbine Muguruza 7-6 (6), 6-2.
Williams was impassive and flat on her feet in the early going against the No. 13-seeded Cibulkova, and the half-empty stands made for a sleepy atmosphere.
''Bor-ing!'' one spectator shouted.
''I was just struggling,'' Williams said. ''I was making so many errors and couldn't pu...