Four more for 24.

Serena Williams, in dogged pursuit of a record 24th career Grand Slam title, powered through the third round of the U.S. Open on Friday with a 6-3, 6-2 win over Karolina Muchova — and now stands just four victories from history.

Williams, 37, will face No. 22 Petra Martic in the fourth round on Sunday.

After needing three sets to get past American teenager Caty McNally in the second round, Williams had little trouble with Muchova in a matinee at Arthur Ashe Stadium. And there is room for improvement: Williams finished with five aces and seven double faults.