Serena Williams continued her ruthless progress in the Miami Masters today with a straight-sets victory over Ayumi Morita.

Williams initially made a sloppy start against her Japanese opponent, dropping her opening service game to fall 3-0 behind thanks to pair of double faults.

Morita failed to build on the early breakthrough and failed to win any of the next six games, eventually losing the first set 6-3 in 37 minutes.

Patience was the key for Serena in the second set as Mortia fought doggedly to hold serve and keep the match competitive.

Williams eventually found her touch at the baseline to earn a crucial break, rattling off accurate winners on both sides of the court.

After consolidating the break on serve, Williams wrapped up a 6-3 6-3 win to progress to the last 16 in just over 75 minutes.