Rafael Nadal came through a major test at the US Open on Friday, recovering from a set and a break down to edge out Karen Khachanov in a third-round epic.
Khachanov – a decade Nadal's junior and up to a career-high ranking of 26 – appeared full of verve as he claimed the opening set on Arthur Ashe Stadium before moving 5-4 ahead against serve in an absorbing second.
However, the defending men's singles champion refused to panic and immediately broke back before levelling the match when play resumed under the roof following a brief rain delay.
Despite the presence of strapping under his right knee, Nadal eventually edged ahead for the first time by taking the third in a gripping tie-break – to the delight of a partisan crowd firmly behind the top seed.
Yet the drama did not end there and Nadal only claimed a 5-7 7-5 7-6 (9-7) 7-6 (7-3) victory – in four hours, 22 minutes – after he had been broken to love when initially serving for the match at 5-4.
He is now set to face Nikoloz Basilashvili in the last 16.
On a cooler, grey day in New York, Khachanov came out firing and deservedly took the first set with his serve and forehand functioning superbly.
The opener was decided when the underdog held in a sensational 12th game that saw Nadal save three set points, two of them in absorbing rallies that prompted huge cheers from a crowd firmly behind the top seed.
If the first set provided high drama, there was even greater intensity in the second as Khachanov moved a break ahead on two occasions only to be pegged back each time.
After rain had forced the closure of the roof at 5-5, it was Nadal who emerged the sharper to steal the set and jump for joy, in spite of increased strapping under that right knee.
He then recovered from 0-40 down at the start of the third, which concluded with a dramatic tie-break won by Nadal at the fifth attempt following a mammoth rally.
Khachanov was guilty of three double faults in the breaker and the youngster's exit appeared inevitable when he fell behind in the fourth.
Nadal stunningly faltered with the match on his racquet, providing his opponent with an unlikely lifeline, but the Spaniard finally prevailed in another tie-break after the crowd had been brought to its feet by a stunning rally featuring a Khachanov tweener.
Nadal  bt Khachanov  5-7 7-5 7-6 [9-7] 7-6 [7-3]
Nadal - 49/38
Khachanov - 66/55
Nadal - 0/3
Khachanov - 22/9
BREAK POINTS WON
Nadal - 5/13
Khachanov - 5/11
FIRST SERVE PERCENTAGE
Nadal - 62
Khachanov - 67
PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Nadal - 71/61
Khachanov - 70/48
Nadal - 161
Khachanov - 156