Once an absorbing opening set went the 25-year-old Spaniard's way, there was no doubting which way the match would go as Nadal cruised to a 6-4 6-1 6-1 victory on Hisense Arena on Monday.
But on Sunday night his prospects of even taking part in the opener looked bleak due to a knee problem.
"Yesterday [Sunday] evening I wasn't a hundred per cent sure I would have chance to play, because with the movement of that knee I felt that I will not be able to play," he said.
Nadal played with strapping on his right knee which he told reporters was due to an unexplainable injury.
"I was sitting on a chair in the hotel, I felt like a crack on the knee, but it's nothing really strange, happens a lot of time with articulation, movement, articulation," he added.
"Nothing strange, I stand up, I felt the knee a little bit strange and moved the leg twice to try and find the feeling.
"After the second time, the knee stayed with an unbelievable pain completely straight."
The Spaniard, whose MRI and ultrasound scan both returned clear when trying to determine the problem, admitted that he was unsure whether he would be able to come through the first round encounter.
"I started the match with a little bit of scare and nervous because I was really disappointed yesterday [Sunday]," he said.
"But after the first 10 games I started to play with normal conditions."
After claiming the first set 6-4 the world No. 2 went on with ease to claim both the following sets 6-1 and despite not knowing what happened to his knee was delighted with the improvement in condition.
"The best thing is I felt the knee very well," he added.
"So it's something that I really don't understand why happened, but I am really happy that today [Monday] I was ready to play and I played a fantastic match."
Although Nadal had an early break in the opening set, for a while it was a contest, with Kuznetsov playing some impressive tennis and hitting the mark with some fierce shots.
But he could not forge a break, or even a break point, when it mattered and Nadal served out for the set before making brisk progress through the next two.
Kuznetsov did not create a break point against Nadal's serve until the final game of the match, when he had two. The first he sacrificed by drifting the ball wide; on the second Nadal unleashed a crosscourt forehand winner.
The game was up for Kuznetsov, and Nadal sealed victory with an ace down the centre.
The Spaniard will now meet Tommy Haas in the second round after the German veteran beat American qualifier Denis Kudla 7-6 3-6 6-0 7-5 on Monday.