World champion Luke Littler beat Nathan Aspinall in a dramatic finale to reach the last eight of the World Series of Darts Finals in Amsterdam.
Littler, 19, trailed 9-8 in a best-of-19 contest that had been close throughout, and held throw in the 18th leg to force a decider.
Needing to break Aspinall's throw to win, he started the final leg with his seventh 180 of the match and checked out 58 for a match-clinching 12-darter.
The two Englishmen had been involved in a World Matchplay classic in July, when Littler threw a nine-darter in the opening leg of an 11-8 victory.
"The pace of the game suits us both, we're good friends and we bring the best out of each other," said Littler, who has a chance to complete a clean sweep of the PDC's premier events in 2026.
"I only played well in the last session [from 6-6 onwards]," he added. "In the first two sessions, I didn't feel confident but I managed to get it to 6-6 and I was very good in the third."
The world number one will meet the former Premier League champion Jonny Clayton in Sunday's quarter-finals. Clayton beat Japan's Motomu Sakai 10-8 and is one of two Welshmen in the last eight, with Gerwyn Price also through after a 10-5 win over Canada's Jim Long.
England's James Wade beat Wessel Nijman of the Netherlands and will face Price. Earlier on Saturday, world number two Luke Humphries lost the deciding leg of his last-16 match to Dirk van Duijvenbode, who now meets Gian van Veen; Ross Smith and Josh Rock completed the quarter-final line-up.
Littler's explanation of the match deserves to be taken at its word. If the two men bring the best out of each other, then neither player's performance is his own. It is produced by his opponent.
On that reading, a contest between them is not a test of skill but a mutual manufacturing arrangement, and the scoreboard records which of the two was the more generous supplier. Aspinall won nine legs. He was therefore outperformed by a man he had spent the evening improving.
It also removes any internal end point. Two players who raise each other indefinitely cannot decline, and a match between them has no reason of its own to finish. Something external must intervene. In Amsterdam, that something was the best-of-19 format.
The Department of Unnecessary Research notes a complication in the player's second statement. Littler also said he played well only in the third session. If both accounts hold, his best was brought out by Aspinall from 6-6 onwards and by nobody at all before that, which leaves two sessions unaccounted for. Governing bodies may wish to establish whether a player can be held responsible for an opponent who starts late.
The quarter-final is on Sunday, against a man under no prior obligation to make him good.