Nick Kyrgios has moved a step closer to breaking his grand slam duck after a stunning fourth-round win over world No.1 Daniil Medvedev at the US Open.

The Australian produced one of his greatest performances to defeat the defending champion 7-6 (13-11) 3-6 6-3 6-2 on Sunday night in New York.

It is Kyrgios’s first win over a world No.1 at a grand slam since his breakout performance against Rafael Nadal at Wimbledon in 2014.

Watch the latest sport on Channel 7 or stream for free on 7plus >>

“Did you like it?” he joked with on-court interviewer Pat McEnroe.

“It was an amazing match, obviously Daniil is defending champion, a lot of pressure on his shoulders, but I played really well.

“I’ve been playing amazing the last couple of months.”

The victory should come as little surprise in the midst of Kyrgios’s best season yet, having beaten Medvedev in Canada earlier in August after having reached the Wimbledon final in July.

Nick Kyrgios has stunned Daniil Medvedev at the US Open. Credit: Getty

“I’m still trying to figure it out, I’m just trying to work hard every day, make every practice session count, getting to sleep,” he said.

“I would probably be out every night before, now I’ve got a great girlfriend and my team … it’s all my team. I’m just really happy.

“I just don’t want to let them down. We’ve been on the road now for four months, we’ve all got families we want to see and I want to make it count.

“This is the last trip before we go back to Australia. I want to go all the way. Hopefully it’s possible.”

Kyrgios received a standing ovation from the packed crowd inside Arthur Ashe Stadium.

“I’m just glad I’m finally able to show New York my talents,” he said.

“I haven’t had many good trips here, I haven’t been able to play good tennis, I’m really glad I’m able to show you guys the work and dedication, finally. It took me 27 years!”

Kyrgios will now face 27th seed Karen Khachanov in the quarter-finals for a spot in the last four, where Casper Ruud (fifth seed) or Matteo Berrettini (13th seed) await.

World No.2 Rafael Nadal looms as the likely finalist from the other side of the draw as the Spaniard eyes off three grand slam titles in a calendar year for just the second time in his career.

But even if a 22-time grand slam champion stands in his way, Kyrgios looks as likely as ever to win his first major.

Against Medvedev on Sunday night he struck 22 aces and hit a total of 49 winners to just 19 unforced errors.