Luke Littler edged out Luke Humphries in a last-leg decider to end the world champion’s winning Premier League run on night nine in Belfast.
Following successive wins in Brighton, Nottingham and Dublin, world number one Humphries had opened up a seven-point lead at the top of the table.
Littler, though, had already beaten Humphries in each of their last three meetings since the world final at Alexandra Palace.
The 17-year-old, who had dropped to fifth in the Premier League table, after last week’s quarter-final defeat to Michael Smith in Dublin, forced an early break to open up a 2-0 lead.
Humphries, however, soon recovered to level the opening quarter-final at the SSE Arena, and the match continued on throw through to the deciding leg.
The world champion sat on a 170 check-out, but missed the second treble 20 which allowed Littler the chance to take out 68 on double 10 and progress to the semi-finals.
Littler hit seven maximums with a match average of 102.02, and goes on to play Michael Van Gerwen, the reigning Premier League champion.
Dutchman Van Gerwen came from 4-2 down against former world champion Michael Smith to win the last four legs, securing victory on a 150 checkout.
