Rafa Nadal has feasted on Russian opposition in the past but Karen Khachanov has almost served up a major US Open upset, forcing the world number one to rally for a breathless 5-7, 7-5, 7-6 (9-7), 7-6 (7-3) third round win.
Not since 2011 has Nadal lost to a Russian, but his string of 16 victories looked ready to end along with his US Open title defence when big-hitting Khachanov came out with guns blazing on Friday (local time).
The 27th seed kept up the pressure throughout a four hour, 23 minute thriller that was the Spaniard's longest ever match at Flushing Meadows.
"I am very happy to be through in a very tough situation," Nadal said in an on-court interview.
"There were some tough moments during the match, but he played aggressive.
"There are things to work on for the next round, but the good thing is I have a chance to improve."
After coasting through his first two matches, Nadal appeared poised for another uneventful day against a 22-year-old he had beaten four times without dropping a set.
That run came to a halt when the Russian took the opener by pounding eight aces past a misfiring Nadal, including one to clinch the set.
The Spaniard found himself in an even deeper hole when Khachanov collected the early break in the second, putting an injury hampered Nadal on the ropes, down a set and a break 5-4.
No player in tennis, however, is more dangerous than Nadal when threatened and — with Khachanov serving for a 2-0 lead — the 17-time grand slam champion's famous survival instincts kicked in and he snatched a clutch break.
Rain began to fall while Nadal celebrated, forcing a delay as Arthur Ashe Stadium's retractable roof was closed, providing the defending champion with an opportunity to regroup.
When play resumed, a focused Nadal went to work, holding serve and then breaking again to get the match back on level terms.
But Khachanov was also in the mood for a fight, forcing the third set to a tie-break which Nadal won 9-7 — with the help of three double faults.
The tie-break seemed to deflate Khachanov as Nadal moved in for the kill, grabbing the early break in the fourth to jump in front 2-1.
But the drama was not over yet and the massive crowd surrounding the stadium waiting to watch the Williams sisters' primetime showdown was forced to wait a little longer.
Khachanov — with Nadal serving for the match — dug deep to break the Spaniard yet again and force another tie-break, but that was as far as the Russian revolt went, with Nadal progressing to a fourth-round meeting with Georgian world number 37 Nikoloz Basilashvili, who earlier prevailed over Argentine Guido Pella in four sets.'Bad things were going through my mind'
Elsewhere, fifth seed Kevin Anderson needed five sets to battle past Canadian 28th seed Denis Shapovalov, winning 4-6, 6-3, 6-4, 4-6, 6-4.
The 2017 US Open finalist will take on ninth seed Dominic Thiem, after the Austrian fought back from a set down against American Taylor Fritz.
Thiem fired 18 aces and broke Fritz five times in the 3-6, 6-3, 7-6 (7-5), 6-4 victory, although it was far from plain sailing for the world number nine.
Trailing 2-0 in the third set, frustration boiled over for Thiem and he destroyed his racket on the ground at the Grandstand court.
"A lot of bad things were going through my mind as everyone could see," an embarrassed Thiem said.
Defending champ advances
"I'm very sorry for that."
In the women's draw, reigning US Open champion Sloane Stephens kept alive her bid for back-to-back titles in New York by defeating former world number one Victoria Azarenka 6-3, 6-4 in a gritty match to set up a fourth-round showdown with Elise Mertens.
The third-seeded American was the sharper of the pair at the outset, firing nine winners and fending off Azarenka's lone break-point opportunity to take the first set in a little over half an hour.
But two-time Australian Open champion Azarenka raised her game in the second set, battling back from a 3-1 deficit to take a 4-3 lead, much to the chagrin of the partisan New York crowd.
A break in the action to close the roof on Arthur Ashe court appeared to bolster Stephens, who tightened up her defence and broke the big-serving Belarusian for a fifth time with a forehand winner to ward off the comeback and go through.
"When things got tough I hung in there," Stephens, who is the highest remaining seed in the women's draw, said in an on-court interview.
"You guys helped a lot," she told the crowd.
A dejected Azarenka said she was disappointed with aspects of her performance.
"At this stage, it's a matter of one, two points, and today I just need to cut down my unforced errors," Azarenka told reporters.
"Those unforced errors that come out, right now they are costing me matches."