World No. 1 and defending champion Rafael Nadal came back from a set and break down to defeat Karen Khachanov 5-7, 7-5, 7-6 (9/7), 7-6 (7/3) to reach the US Open fourth round Friday.
Victory for the 32-year-old put him into the last 16 in New York for the 10th time and on course to add to his 2010, 2013 and 2017 titles.
However, 2009 champion and third seed Juan Martin del Potro, his potential semifinal opponent, also made the last 16 with a 7-5, 7-6 (8/6), 6-3 win over Fernando Verdasco.
Nadal triumphed over Khachanov after an epic 4 hour 23 minute struggle on Arthur Ashe Stadium. He will face Georgia's world number 37 Nikoloz Basilashvili for a place in the quarterfinals.
Meanwhile, Serena Williams turned her 30th career meeting with her sister Venus into a one-woman showcase Friday, reaching the US Open fourth round with a 6-1, 6-2 victory.