Andy Murray had another frustrating afternoon on Louis Armstrong Stadium but did enough to defeat Andrey Kuznetsov and reach the fourth round of the US Open.
There was not the same drama as there had been in round one, when he cramped against Robin Haase and might have lost, but Murray again found himself embroiled in a fight having appeared in total control against a player ranked 96th in the world.
He at least finished the match relatively strongly, recovering from dropping the third set to clinch a 6-1 7-5 4-6 6-2 victory after two hours and 35 minutes.
Much stiffer tests lie ahead, though, with Jo-Wilfried Tsonga his likely next opponent, and he knows he will not be able to afford such lapses if he is to figure in the latter stages of the tournament.
Murray was a picture of calm as he raced through the first set as he wrapped up the opener 6-1 in 31 minutes.
The Scot made a fine start, breaking the Kuznetsov serve at the first opportunity, and he looked to be striking the ball very well.
The Russian fought hard to get on the board in the fourth game and then had one chance to break, but overhit a forehand.
Murray was right on his game, though, and attacked the Kuznetsov serve again to make it 5-1 before serving it out.
Kuznetsov is a slight figure and he was finding more success on Murray's serve - particularly the weak second serve - than on his own delivery.
Murray made the perfect start to the second set with another break before denying Kuznetsov on his fourth break point of the match.
The Scot was powering the ball into the corners off both his backhand and forehand and was keen to come forward and attack the net.
T he second set was much tighter, though, and a loose game from Murray saw Kuznetsov finally take his chance in the eighth game thanks to an untimely double fault.
Murray looked frustrated and from 0-30 in the next game he lost four points in a row and the chance to re-establish his lead immediately.
The 27-year-old has developed a bad habit this season of losing leads, but he did get the second break two games later and served it out 7-5.
Despite getting over the line in the second set, Murray had hit a slump, and it continued at the start of the third.
Kuznetsov exploited the situation to break for a 3-1 lead and memories of Murray's third-set calamity against Robin Haase in round one came flooding back.
At least he appeared to be physically well this time and, after battling to stop the rot with a hold in the sixth game, he broke to love to get back on track.
However, the up-and-down form that has plagued his season was still very much in evidence and cost him dearly in the 10th game.
Two loose shots gave Kuznetsov two set points and Murray did not even make the Russian work for it, serving a double fault to lose the set 6-4.
Perhaps not surprisingly given his results this season, Murray appears to be lacking belief in the big moments, and he must have been furious with himself for being extended to four sets.
He headed off for a bathroom break, a tactic that had helped him so much in his final win over Novak Djokovic here in 2012.
And Murray was quickly ahead in the third set, breaking for 2-1 when Kuznetsov drilled a forehand over the baseline.
The Russian was under real pressure now and, although he saved two break points in the fifth game, one with a brilliant drop volley, he then threw in successive double faults to hand Murray what was surely a match-winning advantage.
Still it was not entirely straightforward as Murray immediately surrendered one of the breaks but he got it back quickly and took his first match point with a reaction volley.