Scotsman – after a struggle
But that was how it turned out in their thirdround clash. Lewis let a 3-1 lead slip and found himself 2-0 down in the deciding set, but the Welshman dug deep to win in a tie-break.
Lewis edged the first set 3-2 before racing through set two 3-0, hitting an 11-darter in the first leg.
A 78 finish helped Gurney win the third set in five legs but, after the Northern Irishman missed four darts to level set four, Lewis landed double 16 to move within a set of victory.
Gurney then enjoyed a purple patch, which he kicked off with a 160 checkout, that saw him win eight of the next nine legs to put him 2-0 up in the deciding set.
However, he missed a dart at double 16 to win before Lewis embarked on a remarkable comeback.
Lewis used just 58 darts to win the four legs he needed to secure an incredible win.
Earlier, another seed, the 25th-ranked Alan Norris was knocked out by Ryan Joyce.
Joyce came from 2-0 down to win.
Joyce had moved in front by landing tops after Norris had hit a 180 to leave double three.
Norris edged the sixth set before Joyce won the deciding set.
There was no such drama for Dave Chisnall, though, a 4-0 winner over Kim Huybrechts.
Chisnall bossed his third round meeting with the Belgian from start to finish.
Ryan Searle moved into the last 16 with a comfortable 4-1 victory over William O’connor.