Nick Kyrgios was in disbelief after reaching his first grand slam semi-final with a Wimbledon victory over Cristian Garin, suggesting his best chances of major success had been wasted.

Kyrgios produced an impressive display on No. 1 Court to down his Chilean opponent 6-4 6-3 7-6 (7-5), becoming the first unseeded Wimbledon semi-finalist since Rainer Schuttler and Marat Safin in 2008.

The Australian, who had lost two previous grand slam quarter-finals (at Wimbledon in 2014 and the Australian Open the following year) has courted controversy during a box-office run at SW19, spitting in the direction of a spectator during his opener last week before labelling Stefanos Tsitsipas "soft" after an ill-tempered third-round match.

And the 27-year-old, who took a moment to sit and savour his win before conducting his court-side interview, thought he had squandered any chance of grand slam success earlier in his career.

"Amazing atmosphere out here again, I just never thought I'd be at a semi-final of a grand slam, honestly, I thought my ship had sailed," he said.

"You know, I didn't go about things great earlier in my career, and may have wasted that little window.

"But I'm just really proud of the way I've come back out here, and of my team."

Kyrgios put the rows and trick-shots to one side during a professional performance, serving 17 aces and saving eight of the nine break points conjured by Garin.

Asked how he had found consistency without working with a full-time coach, Kyrgios said: "I don't have a coach, I would never put that burden on someone!

"Each and every one of my team plays a very important role, [but] I feel like no-one knows my tennis like I do. 

"I've been playing this sport since I was seven, and to reach a semi-final of a grand slam… I'm pretty happy."

Kyrgios' clash with Garin represented Wimbledon's first quarter-final between two unseeded players since 2008 (Arnaud Clement v Schuttler), and the Australian said he never felt in control against a tough opponent despite posting a straight-sets win.

"Honestly, I felt I was playing on the back foot a lot, he's a hell of a player, he's obviously feeling very confident, it's been a hell of a tournament from him to make the quarter-finals," he continued.

"I felt I got a bit lucky on a couple of break points here and there, it could easily have been him standing here.

"I'll just take that and prepare for my next match.

"I don't want to think about the semi-final just yet, there's a lot to be done from now until then. We'll go back, my dad will cook dinner as always, we'll watch a movie and just chill out. That's it."