Allen, looking to claim his fifth world championship title, started their second session with a two frame advantage and took the ninth frame to lead 6-3.

But the world number three lost the next four in a row during an error-strewn afternoon as a ruthless Selby turned on the style.

Only five frames were played in a lively and at times light-hearted session that lasted over five hours, with the record for the longest frame in the match broken three times.

The first four frames - including a delightful 95 from Selby to narrow the score at 6-5 - took over two hours to complete as both players slogged out tricky snookers with two stalemates delaying the action further.

Tournament organisers decided to end the afternoon three frames short of its allotted schedule with the players set to resume on Saturday from 10am BST.

The winner will face either Luca Brecel or Jiahui Si in Sunday's final.