Nathan Aspinall momentarily halted his epic World Championship clash with Luke Littler to laugh at the brilliance of the darts on display. Both players were on the verge of rare nine-darters in the second leg of the fourth set in Littler's breathless 5-2 victory.

Littler defied Aspinall's strong start and raced into a 2-0 lead. The 17-year-old sensation averaged just over 111 in the first set, which would have landed him in the top three one-game averages in the tournament's history.

Aspinall won the third set and was soon in hysterics at the excellence on display. The Asp won the first leg but Littler responded by throwing T20. Fittingly, Aspinall responded with exactly the same score.

But Aspinall was stunned when Littler approached the board and once again bagged 180. The 33-year-old laughed at the incredulity of the situation and had to compose himself before throwing his first dart.

To roars from an electric Alexandra Palace crowd, Aspinall threw T20 before halting to regain composure. He turned to the fans and began laughing again.

Unfortunately, the World No. 12 missed T20 with his next throw before landing his final attempt in D1. Aspinall laughed again before sarcastically waving his hand as if to say: "Oh well..."

Littler failed to land a nine-darter with his next two throws agonisingly missing T20. Not quite as amused as Aspinall, the Nuke puffed his cheeks before sharing a friendly high-five with his opponent.

Littler went on to win the leg to level the set at 1-1. He raced into a 4-1 lead but missed a golden opportunity to win the match in what should have been a comfortable ending.

But Aspinall taking the sixth set only prolonged Littler's crowning moment. The Warrington-born star went on to win 5-2 and will face Stephen Bunting in the semi-final. Michael van Gerwen or Chris Dobey could await in another Ally Pally showdown next week.

Asked afterwards about Aspinall laughing during the fourth set, Littler said: "I wouldn't say it's hard to focus. Obviously each time we've won a set, we'll give each other a fist bump. Once Kirk says game on, that's when it's game on. Afterwards, we'll be fine.

“We’ve both played very well there. I’m so glad to win and the crowd were chanting for Nathan, they wanted the comeback. But I had to finish it.

“[The expectation] has been fine. Obviously the Ryan Meikle game was tough but ever since, it has just felt like last year. I’m playing with absolute confidence. When they’re going in, I’m playing with freedom. Now it’s about looking on to the semi-finals.”

Quizzed on facing Bunting’s army of fans, Littler jokingly eye-rolled to the crowd before adding: “They’ve been really good to me tonight. They’ve been good to Stephen. Obviously they can take their pick with whoever they want to support tomorrow. I can see quite a few Nuke shirts in here, so I think I’ve got the better!”