Raymond van Barneveld suffered a shock 5-4 defeat to Ian White on the opening night of the Grand Slam of Darts.
The five-time world champion, a semi-finalist at the event back in 2009, was distinctly out-of-sorts and White capitalised superbly to take a giant step towards qualification from Group B.
Van Barneveld was always playing catch-up and only a composed 14-dart checkout under pressure squared the match at 4-4 and took the contest into a deciding leg.
However White, who was invited to the tournament at late notice following an injury to Simon Whitlock, took out double 19 at the second attempt to seal a famous win.
James Wade was also given a scare before edging past Dave Chisnall 5-4 later on Saturday night.
In a high-quality match, Chisnall missed a dart for victory in the eighth leg before Wade regathered his composure to prevail.
An inspired 161 checkout from Wade saw him break early but the impressive Chisnall responded instantly to level at 2-2.
Neither player had missed a double in the opening seven legs, however Wade, despite missing four in the eighth, took the match into a deciding leg.
'The Machine' started the decider with a 180 and with Chisnall well back, closed out victory on double top.
The first surprise of the tournament came when two-time world champion Ted Hankey was whitewashed by Dean Winstanley.
Lakeside finalist Winstanley, making his first live appearance on stage at a PDC event, capitalised on a woeful performance from 'The Count' to prevail 5-0.
Hankey missed 14 doubles throughout the match and now faces an uphill task to qualify for the knockout phases.
Local favourite Wayne Jones was a popular winner in the tournament's opening match as he overcame Northern Ireland's Brendan Dolan 5-2.
Mark Walsh secured a debut victory at the event after he overcame Tony O'Shea 5-2 in the second match of the evening.
'Walshy' produced an accomplished performance which included checkouts of 61 and 78 and three double-top finishes.
Reigning champion Scott Waites began the defence of his title with a 5-3 loss to Michael van Gerwen, with the young Dutchman storming into a 4-0 lead before holding off a comeback to complete an impressive win.
Nigel Heydon defeated Gary Anderson 5-3 to claim the biggest win of his career a week after winning through the Wildcard qualifier in Crawley.
And Justin Pipe impressed with a 5-1 defeat of 2008 runner-up Terry Jenkins, which leaves the Ledbury man needing to defeat Chisnall on Sunday night to remain in the hunt.
Sunday's afternoon session sees three-time Grand Slam of Darts winner Phil Taylor in action as Groups E-H play their opening games.