Serena Williams reaches fourth round of Australian Open in 47 minutes

Defending champion Serena Williams made light work of her third-round match against Daria Kasatkina at the Australian Open by sealing a 6-1 6-1 triumph in under an hour in Melbourne.

The world number one, who claimed three Grand Slam titles last year, broke serve at the first time of asking and stormed to a 3-0 lead.

Kasatkina managed to get one game on the board, but it did not inspire a comeback as Williams broke again to take a one-set lead in 24 minutes.

The second set mirrored the first as the 21-time Grand Slam champion went a break up immediately and was rarely troubled by Kasatkina, who failed to muster a single break point.

Williams took just 47 minutes to grab a place in the next round of the tournament.