The teenager required treatment on his knee during the second set of his 6-4 7-6 (7-2) 6-4 win over Italian Andreas Seppi in the second round on Thursday.
Asked afterwards how it felt, Kyrgios said "It's feeling OK now. A bit sore after when I fell on it. It's OK now."
Kyrgios beat Russian 21st seed Mikhail Youzhny in the first round and Seppi, who has struggled this year, was no match for the 19-year-old.
The Wimbledon quarter-finalist, who hit 22 aces and 41 winners, said he was confident he could go deep at Flushing Meadows.
"I think if I play like I played today, you know, just do whatever I can to recover and keep having fun, I guess, I can make an impact, yeah," Kyrgios said.
Kyrgios gets another seed in the third round, facing Spanish veteran Tommy Robredo for the first time.
But the teenager refuses to get carried away too soon.
"I keep playing quality opponents," Kyrgios said.
"I'm playing Tommy Robredo next. He's probably one of the most experienced players on tour. He's still playing some really good tennis. I know I can't get too confident.
"I'm going to go out there, have fun, just play my game and see how it goes."