Jonny Clayton ended Michael van Gerwen's perfect Premier League semi-final record to set up a final showdown with fellow debutant Jose De Sousa who beat Nathan Aspinall.
Van Gerwen had secured a record-equalling eighth first-place finish in the league phase on Thursday, but missed out on the last four in 2020 - the first time he had failed to reach Finals Night.
He returned to the finale and with a 100 per cent record in his previous seven semi-finals had high hopes of a record-equalling sixth title, that would have taken him level with Phil Taylor's haul.
However Clayton has been riding the crest of a wave since winning the World Cup of Darts with Gerwyn Price last year.
With his semi-final spot already securing him the biggest pay-day of his career, the Masters champion rallied from 7-6 down to win four of the legs five legs and guarantee himself at least £120,000 and a shot at the £250,000 first prize.
Grand Slam of Darts champion De Sousa joined him with a 10-9 win over last year's runner-up Nathan Aspinall to ensure that for the second year in succession there would be two debutants in the final, and another first time winner after Glen Durrant's triumph last year.
Fabulous Ferret ends Van Gerwen's quest
Clayton continued his impressive record against Van Gerwen, beating the five-time champion for the second time in this season's Premier League to reach his second major televised individual final.
A high-quality contest saw both men average north of 100 and share four 100+ finishes, with Van Gerwen first to strike.
Having set a new record for 100+ finishes in the tournament, MVG kicked off with a classy 108, giving him a 24th three-figure outshot of the competition but Clayton hit straight back - pinning the bullseye for a brilliant 127.
The Welshman struck the first blow when he took out 88 for the first break only for Van Gerwen to hit back with a 12-darter to level at 3-3.
Van Gerwen's sensational 140 finish courtesy of a pair of double tops, maintained a level contest but he missed a dart to retake the lead. Clayton's 14-darter put him in front and he consolidated to take a 6-4 lead into the interval.
The Dutchman returned with his first back-to-back legs of the match to restore parity and for good measure added a third to seize control when he pinned bullseye for a 7-6 lead - but he was to get just one more leg.
Clayton stopped the rot as the pair traded blows before Clayton landed the decisive punch. With the match all square at 8-8, the Ferret produced a brilliant 11-dart leg against the throw to stand one away from the finishing line.
There we no nerves from the Welshman, who fired a brilliant 121 finish to seal his place in the final and inflict just a third Finals Night defeat on Van Gerwen who also becomes he first table topper to not make the final.
De Sousa edges Asp to keep debut dream alive
De Sousa held his nerve in a last leg decider to deny Aspinall the chance to go one better than last year, edging out The Asp with a 10-9 victory.
Like Clayton, De Sousa is enjoying a debut to remember in the Premier League, and there was little between himself and Aspinall who met for a second successive evening following The Special One's win on Thursday.
Leading 2-1, De Sousa - who took out 106 for his first leg - miscounted on 37 to hand Aspinall a chance to level which he did not pass up. The man from Stockport continued to play catch-up, levelling at 3-3 when he needed just five darts from 296 for a brilliant 11-dart leg
Aspinall broke for a 5-4 lead as the Portuguese Man O'Scores lost his way a little to leave Wayne Mardle speechless for a second night.
There remained little between the pair, a frantic 14th leg saw both men fritter away chance before Asp held on to level at 7-7
Trailing 8-7, Aspinall went six darts of the way to the competition's third perfect leg, and while he fell short, a 10 darter turned the match into a best of three contest.
De Sousa kept his nose in front thanks to a brilliant 121 but The Asp ensured the match went the distance where the Portuguese thrower stayed calm to claim his place in the final.
Darts is back on your Sky Sports screens in July, with nine days of coverage from the iconic Winter Gardens and the World Matchplay - the action gets underway on Saturday July 17