Andy Murray believes his ability to capitalise on Nick Kyrgios' "dips" were crucial in his four-set win at the US Open on Tuesday.

The British third seed claimed a 7-5 6-3 4-6 6-1 win over Kyrgios in an entertaining first-round clash in New York.

Murray, a two-time grand slam champion, said the unpredictable Australian simply lost concentration in patches during the contest.

"I actually don't think that he plays that high-risk tennis to be honest. I think it's more the ups and downs," he said.

"Like when he's on, he doesn't play high-risk tennis. I mean, he hits the ball, you know, with a lot of spin on his forehand, a lot of safety. And his backhand is a really good shot. I mean, he hits it flat.

"The two strokes are completely different. One's very sort of spinny and the other one is totally flat.

"He has an excellent serve, one of the better serves on the tour. Just sort of five- or 10-minute periods in the match, it happens a little bit too often, where he has dips, misses a few serves, like gets distracted or loses concentration. That's where I capitalised tonight I think."

Murray was composed throughout as Kyrgios complained about the crowd and tried to nap during changes of ends.

The 28-year-old said he expects a different type of contest when he faces Adrian Mannarino in the second round.

"I expected a very, very tough match," Murray said.

"But it was hard for me to kind of go out there and be like really aggressive or play the way I wanted to because it's very hard against him. He's a very powerful guy. He goes for unpredictable shots. You don't know exactly what to expect each point.

"A lot of the time I felt like I was just reacting and ended up having to do quite a bit of defending and running because of that.

"But against him, you're going to have to play that way at times. So, yeah, hopefully in the next round, maybe I'll have a little bit more time, be a little bit more comfortable out on the court, be able to play a little bit different."