James Wade and Raymond van Barneveld were the major first-round casualties at the World Grand Prix in Dublin.
Champion in 2007 and 2010, Wade looked to be in total control of his first round clash with Colin Osborne as he pulled a set and two legs ahead without ever really moving out of first gear.
But, as Wade took his eye off the ball, Osborne staged an extraordinary fightback and, having pinched the next two legs to get back on terms, levelled at one set all with a 108 check-out.
A clearly distracted and upset-looking Wade then wilted in the deciding set and Osborne reeled off three legs in succession to seal a fine victory.
Osborne now faces Paul Nicholson after the Australian brushed aside Northern Ireland's Michael Mansell 2-0.
Van Barneveld was made to pay for missing a dart at tops for the first set as Ian White came storming back with check-outs of 112, 132 and 144 to complete a stunning 2-0 win.
Like Osborne, Wes Newton also came from a set and two legs down to progress as he found his form in the nick of time to overcome the ever-fluent Ronnie Baxter.
Adrian Lewis was made to battle before finally seeing off Welshman Richie Burnett, but having been taken to a decider the world champion produced a 10-darter on his way to a 2-1 success.
Michael van Gerwen edged a high-quality contest with 2004 champion Colin Lloyd, the Dutchman recovering well after losing the first set and closing out the contest in style with a 101 finish.
Mark Webster's miserable run continued as he was beaten 2-0 by 2012 World Championship finalist Andy Hamilton, while Steve Beaton proved too strong for Andy Smith as he won 2-0.