Serena Williams has equalled her most-lopsided victory ever in 30 professional meetings with sister Venus, beating her 6-1 6-2 in the third round of the US Open.

Serena shook off an early ankle injury to win seven straight games and seize control in perhaps her most dominant performance since giving birth to her a daughter a year ago.

Friday was the 18th time Serena has beaten her older sister in 30 career meetings.

The sisters’ earliest meeting in a grand slam tournament in 20 years was over early, with Venus unable to do anything to blunt Serena’s power, even after the crowd tried desperately to get behind her early in the second set.

They hadn’t played this early in a grand slam since Venus won in the second round of the 1998 Australian Open in their first meeting as pros, and only once in the next two decades had either won so decisively, when Serena won by the same score in a semifinal victory in Charleston, South Carolina, in 2013.