Mensur Suljovic produced an incredible comeback to stun Vincent van der Voort and reach his first major semi-final at the World Grand Prix at Citywest in Dublin, as Robert Thornton and Mark Webster won in a sudden-death leg and Michael van Gerwen continued his quest to retain the title.
Austrian star Suljovic has emerged as a contender at the top level by reaching the UK Open and World Matchplay quarter-finals in his rise into the world's top 32 this year.
He will now compete for the first time in a televised semi-final on Friday after coming from a set down and two legs behind to win a remarkable nine straight legs against van der Voort.
The Dutchman hit three 180s and a 128 bull finish as he won the quarter-final's first set 3-1, before taking out 156 and double four to move two legs up in set two.
However, a string of missed doubles to claim the set in the third leg proved the turning point as Suljovic took out 89 on the bull to hit back.
The Austrian then finished 60 and 88 to take the set 3-2, before winning the third without reply to move 2-1 up in the contest.
A seventh straight leg moved Suljovic ahead in set four, before he took out double eight to move 2-0 up and then sealed his comeback in stunning fashion with a 170 checkout.
"This feeling is very, very nice - it's the best moment of my career," said Suljovic. "To be in the semi-finals in Dublin is amazing for me and I'm so happy.
"Vincent gave me the chance in that second set and I came back and won the set, and when he missed doubles in the third set I was telling myself I had the chance.
"That finish at the end was very nice and I was so happy when I hit the bull - maybe I can go on and win now!"
Suljovic will now play Robert Thornton in the last four, after the former UK Open champion held off Ian White's brave challenge to claim victory in a deciding leg of their five-set thriller.
Thornton kicked off with game with a 160 score and took the first set 3-1 before missing two darts to double his advantage in the second, as White finished a stunning 158 checkout in the decider to level.
The Scot then won the third without reply with a superb set, only to see White edge the fourth in another deciding leg - despite four 180s in five legs from his opponent - to send the match all the way.
Thornton, with the advantage of throw, led 1-0 and 2-1 before White hit a maximum as he levelled to make the match a one-leg shoot-out which the Scot took on tops.
"It was a great scrap and I probably knew it would be that way, and I loved it," said Thornton. "In that final set I just had to hold on to my throw because I had the advantage, and in the end it paid off.
"Ian's one of the most consistent players you'll come up against and I'm quite happy to get this win.
"I'm enjoying this event and I like the double-start format, and hopefully I can keep this going now but I've got to take it one match at a time and concentrate on the semi-finals."
White had knocked out World Champion Gary Anderson on Wednesday night as he reached his second successive major quarter-final, after also progressing to the last eight in the World Matchplay in July.
"I'm disappointed that I didn't get through because I want to get past the quarter-finals," he said. "I struggled all the way through and wasn't starting like I did against Gary, and that was my downfall."
Mark Webster also enjoyed success in a dramatic sudden-death leg as he held off Jelle Klaasen's fightback to reach his first major ranking semi-final for nearly four years.
The Welsh left-hander has overcome Stephen Bunting and Adrian Lewis already in the double-start event this week, and continued his resurgence with another fine display.
He dropped only one leg as he took the first two sets, hitting finishes of 108 and 105 in the process, with an 11-darter from Klaasen the only resistance as the Welshman took command.
Klaasen then hit back to take the third 3-0, and came from a leg down to win the fourth 3-1 as his accuracy on double 18 - which has helped him to overcome Brendan Dolan and Dave Chisnall - returned.
Klaasen then led 1-0 in the final set, only for Webster to finish double ten and 86 on the bull to move ahead, and though the Dutchman produced another outstanding 11-darter to force a one-leg shoot-out, it was the left-hander who punished five missed opening doubles from his opponent with tops for victory.
"I played solid and I'm really pleased," said Webster. "At 2-0 up I started missing my double in, but I can't be too critical of myself because I dug in.
"This is the beauty of the PDC - opportunities are always there for someone and thankfully I'm taking mine at the minute. I feel really good and I've worked hard, so bring on the semi-finals."
Reigning World Grand Prix champion Michael van Gerwen set up a tasty semi-final against Webster with a straight sets win over another Welshman, emerging youngster Jamie Lewis.
After needing 11 darts at a finishing double before he won the opening leg, van Gerwen pulled clear with 180s in the next two to claim the first set without reply, and he also led 2-0 in the second before Lewis got off the mark.
The Dutchman, though, hit a 165 score to set up 24 in the fourth leg as he wrapped up the set to double his advantage.
Lewis battled back by sharing the first two legs of set three, with a 74 checkout moving van Gerwen 2-1 up before the Welsh ace took out 109 to keep his hopes alive.
Van Gerwen, though, was merciless as he wrapped up victory in stunning fashion with a spectacular 160 checkout to continue his bid for a third Citywest Hotel triumph.
"It's fantastic to be through to the semi-finals," said van Gerwen. "I played quite well - only the first leg was a bit of a disaster for me, but I still won the leg - and Jamie didn't perform really well and he can do a lot better.
"I'm proud about this win and with my confidence at the moment. Mark's a fantastic player and he showed his class tonight, but I will be the huge favourite against him and I need to perform really well."
