Smith produced an inspired display to curtail Clayton's hopes of scooping a fifth televised title in 2021, defying a 102.48 average and 14 maximums from 'The Ferret' to reach the quarter-finals.

The Welshman raced into a commanding two-set lead with a staggering 110.6 average, only for Smith to reel off three consecutive sets to seize the initiative.

The contest then exploded into life as the pair traded three consecutive ton-plus finishes in an extraordinary sixth set, but following a topsy-turvy finale, 'Bully Boy' kept his cool to record a famous victory.

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This was billed as potentially the match of the tournament and it certainly lived up to the hype, featuring 25 maximums and five ton-plus finishes.

The quality was relentless, but having suffered an agonising tie-break defeat to eventual winner Rob Cross in the 2018 event, Smith was relieved to be on the winning side on this occasion.

"That deserved to be the final," Smith told Sky Sports.

"That game felt like the Rob Cross one in 2018. I thought I've been here before in this situation when I had the 96 to take Rob out, but luckily enough I got away with it and I got through.

"Going into that match, I just kept saying to myself: 'I've got a game to beat anyone, I've got to keep believing and keep doing it'.

"My scoring wasn't the best tonight, but I did it at the right time. I hit the right shots at the right time, and I'm just really chuffed that I got the win.

"Jonny has probably been No.1 or No.2 all year. To get that win was massive for my confidence, and the way I did it with 72, 64 and 68 [finishes] - those last darts at double were going in."

Smith - a runner-up at Ally Pally in 2019 - is a perennial contender in the latter stages of major events, but a maiden televised title has thus far proven elusive.

The 31-year-old has succumbed in five major finals since 2018, but as he embarks on a tantalising last-eight showdown against defending champion Gerwyn Price on New Year's Day, he is philosophical about his prospects.

"I've been here a long time now. I think it's my 11th World Championship," Smith added.

"It is coming [a major title], but I'm not going to rush it, I'm not going to want it too much. That is what I have been guilty of in the past, wanting things too quick.

"I just want to keep focused, keep doing what I've been doing for the last 12 months. You can see it is finally coming through into my game now.

"I've had a really bad World Championship in the last two years, and I'm finally giving a good account of myself this year, so no matter who I get or what I do, as long as I play darts on this stage, I'm happy."

Mardle: It was 36 legs of sexy darts!

Smith has been touted as a future world champion since bursting onto the scene almost a decade ago, such was his prodigious talent.

He now appears to have the temperament to match his outrageous ability, and Wayne Mardle believes 'Bully Boy' possesses all the credentials to lift the Sid Waddell Trophy on January 3.

"I think he is more mature. He is not the finished article. He is still in his early 30s which again is sickening because he's got so much pedigree already," Mardle quipped.

"He has been in a final here, a final in the Premier League, the final of the Matchplay. He has nearly won it all, but unfortunately for him has not won anything yet.

"He is a winner on tour, seemingly every single season. He's got to believe he's a winner, because he is.

"When he wins, it will be: 'Well of course he won, he is brilliant', but until he actually does it, whether he knows he can or not, we don't know.

"The standard that he plays at, of course he can win it. Believe it Michael!"

Join us for the conclusion of the World Darts Championship at Alexandra Palace on Sky Sports Darts. Check out daily Darts news on skysports.com/darts, our app for mobile devices and our Twitter account @skysportsdarts