Andy Murray revelled in his classy performance as he triumphed over young Australian Nick Kygrios.

The Scot demolished Kygrios 7-5 6-1 6-4 as the world number two put in another complete performance to move into the Wimbledon quarter-finals and he said overcoming the youngster's powerful serve in the first set was key.

Kygrios looked up for it in the first set, but became frustrated as his quality serve failed to get the better of Murray.

Once the first set was won, Kyrgios looked like - and later admitted - he had lost all self-belief and crumbled to a straight-set defeat.

Not that you could take anything away from the brilliant Murray, who smashed 36 winners and allowed just six unforced errors on the way to the win.

"I thought I played well. The first set was obviously key. He served extremely well in the first set," Murray said. 

"He was up in the high 80s for first-serve percentage, which to win a set against someone serving like that is big and totally changed the way the match went, I think.

"I played a good return game at 6‑5, and that was it."

When prompted, Murray said Kyrgios had to continue to work on the mental side of the game to stay in matches all the way through, but was not sure what the best approach to find a solution would be.

"Everyone's different. It's about finding the right people to help you with different things," he said.

"Everyone's different in terms of how they improve and address their problems."

But on his side of the net, Murray said it was important not to be distracted by the mood swings of his opponent.

"[You] just keep your head down really. Concentrate on your side of the court. Control what you can, basically," Murray explained.

"You can't always control what your opponent's doing or how your opponent's playing. But you can apply yourself to every single point and fight for every point. Don't give up any cheap games or anything like that.

"I did a good job of that today. I don't think I gave up a breakpoint. I was solid on my serve, then created a little chance end of the first set.

"After that in the second set especially, I just tried to make as many balls as possible. That was it."