Ian White from Stoke-on-Trent is through to the quarter-finals of the World Matchplay in Dublin.
He came from a set down to Michael Smith 3-1.
White led 2-1 early on, only to miss his chance to close out the set as Smith capitalised on two missed doubles with a 14-darter before winning the deciding leg on double ten.
White, though, opened set two with a 12-darter to spark a run of seven successive legs as he moved into a 2-1 lead in the game and also took the advantage in set four.
Smith hit back to win two of the next three as he saved the set, but the fightback was brief as tops sealed White's spot in the last eight.
"I'm delighted to win but it was hard work," said White. "Michael's my practice partner and a close friend so it's hard playing someone you know so well.
"I thought I could have won the first set, but I kept myself focused and not many players win seven legs in a row against Michael Smith.
"I wanted to get towards the latter stages to give myself a chance and I'm glad I'm still going. It's coming up to the end of the year so every major tournament is big and I want to prove to everyone that I can play up there."
White will now play Chris Dobey, who reached his third televised quarter-final with a superb 3-1 victory over two-time World Champion Gary Anderson.
The Scot, a former Dublin finalist, defied a showpiece 134 checkout from Dobey to claim the opening set 3-2, only to see the Newcastle youngster come from 2-1 down to level in the second.
Dobey then finished 90, 60 and 110 to win the third without reply, before securing his last eight place by claiming set four with a 3-1 scoreline.
"I think my overall performance was pretty good and I'm delighted to have won," said Dobey. "I knew I had the game to beat Gary and I had to keep my cool, and it's up there with my best performances on stage.
"It means a lot to me. This is a great competition to be in and I like the double-start format - I think it suits my game. I'm not here to make the numbers up, I'm in it to win it but I'm not going to look any further forward than the next game."
The second round concludes on Wednesday with the remaining four matches, headlined by the clash between World Matchplay champion Rob Cross and reigning Lakeside Champion Glen Durrant.
Former World Grand Prix finalists Dave Chisnall and Peter Wright will play Stephen Bunting and Jermaine Wattimena respectively, while UK Open champion Nathan Aspinall is up against Danny Noppert.
2019 BoyleSports World Grand Prix
Tuesday October 8
Second Round x4
Mervyn King 3-1 James Wade (2-3, 3-2, 3-1, 3-0)
Ian White 3-1 Michael Smith (2-3, 3-0, 3-0, 3-2)
Michael van Gerwen 3-0 Jeffrey de Zwaan (3-0, 3-1, 3-1)
Chris Dobey 3-1 Gary Anderson (2-3, 3-2, 3-0, 3-1)
Wednesday October 9 (1900 start)
Second Round x4
Danny Noppert v Nathan Aspinall
Dave Chisnall v Stephen Bunting
Rob Cross v Glen Durrant
Peter Wright v Jermaine Wattimena
Second Round - best of five sets, best of five legs per set. All legs must begin and end with a double.