Serena dials up another ace effort

Williams unleashes power serves to send Sharapova reeling

Serena Williams stuck out a fist in mock triumph and mouthed "C'mon!" - careful not to push her point too far.

The 33-year-old Williams was closing in on her 19th Grand Slam singles title, her 16th straight win over Maria Sharapova and her sixth Australian Open championship when she was docked a point by the chair umpire for hindrance - for yelling in celebration too early when she thought she'd hit a service winner.