Michael Smith had the best average of the quarter-finals as he knocked out the defending champion ©Getty Images

Defending champion Gerwyn Price has been knocked out of the World Darts Championship by an inspired Michael Smith, who four times came from behind to clinch victory and a place in the final four.

Price produced a nine-dart finish at one point in the high-quality quarter-final, but still could not defeat Smith, ending his defence of the Professional Darts Corporation world crown at London's Alexandra Palace. 

Welshman Price won sets one, three, five and seven to four times take the lead, but each time Smith came roaring back.

England's Smith, the runner-up at the 2019 World Darts Championship, had a three-dart average of 101.94 across the nine-set thriller.

It was the best average of the quarter-finals.

Compatriot James Wade awaits in the semi-finals.

Wade breezed past Mervyn King 5-0 in an all-English quarter-final.

The other semi-final will be an all-Scottish affair between Gary Anderson and Peter Wright, two former champions.

Wright came from two sets down against 23-year-old year Englishman Callan Rydz to win 5-4, while Anderson beat England's Luke Humphries 5-2.

The semi-finals are scheduled tomorrow, ahead of Monday's (January 3) final.