NEW YORK — Serena Williams equaled her most lopsided victory ever in 30 professional meetings with sister Venus, beating her 6-1, 6-2 on Friday night in the third round of the U.S. 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 daughter a year ago Saturday.

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.

“It’s not easy,” Serena said, despite how easy it looked in a match that lasted just 1 hour, 12 minutes.

They had not 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.

Serena will next face Kaia Kanepi of Estonia.

Serena leads the series 18-12 with her sister, 11-5 in Grand Slam tournaments.

But this was the type of tennis that has brought her to 23 Grand Slam singles titles, the ability to pound balls all over the court and chase down the rare shots that looked like they might get past her.

“This was my best match since I returned,” she said.

Steady Sloane

When Victoria Azarenka started off with a 101 mph serve and then attempted a drop shot one stroke later, Sloane Stephens charged ahead to extinguish it.

The defending U.S. Open champion sprinted from the baseline and smacked a forehand cross-court winner to win 6-3, 6-4.

Her movement was superb and her play from the backcourt was typically effective against Azarenka, 29, but the match was won on close points. Stephens advances to face 22-year-old Elise Mertens of Belgium in the fourth round Sunday. A possible matchup with Williams looms in the semifinals for the No. 3 seed.

Rafa responds

Rafael Nadal stretched his arms out wide and tossed his head back in jubilation.

His match with Russian Karen Khachanov preceded the night’s main event between the Williams sisters, but it turned into one of the matches of the tournament, a 4-hour, 23-minute battle that felt like anything but an undercard. The defending champion staved off a gutsy effort to prevail, 5-7, 7-5, 7-6 (7), 7-6 (3).

The top seed advances to play Nikoloz Basilashvili in the fourth round.

Nadal was pushed to play his best tennis by the 22-year-old from Moscow, and responded.

The No. 1 player in the world wore tape just below his right kneecap for almost the entire match but did not appear hampered.

He was one point away from dropping the fourth set as well, but the three-time Grand Slam champion escaped again in a tiebreaker.