Welding was not at his best against Kuczynski

Welding, who upset world number one Colin Lloyd in the first round, moved ahead for the first time in the fifth set with a double 10 finish.

Kuczynski was unable to respond and Welding reeled off the next three legs.

Welding will face Wolverhampton's Wayne Jones in the last eight after he beat Welshman Steve Alker 4-1.

Two-time champion John Part overcame the challenge of Chris Mason to book a third-round date with Wayne Mardle.

Part used all his experience to clinch a 4-3 win over the battling Mason.

Mardle, the world number six, sealed a 4-1 win over Belgium's Erik Clarys in the evening session's first game.

And in the afternoon session there were second-round wins for Andy Hamilton, Andy Smith and Alan Warriner-Little.

Part kicked off with a 113 checkout on his way to taking the opening set but Mason was soon back on level terms.

The next two sets were shared before Part struck what looked to be a decisive blow with double eight, which moved the Canadian within one set of victory.

I don't care about performances - a win is a win Wayne Mardle

But Mason's never-say-die attitude shone through again as he battled to a 3-1 success in the sixth set.

Part, however, then upped his game to take a two-leg lead in the decider. "Mase the Ace" pulled one back but Part closed out a memorable encounter with a 72 checkout.

"I just tried to be consistent and I think I was fairly successful," said Part.

"When Chris missed double top and I levelled up at 2-2 (in sets), that was the turning point for me."

Mardle, one of the game's most colourful characters, lost the first set against Clarys but then turned on the style in the next three sets, reeling off nine straight legs.

The next four legs were shared before Mardle took out double eight to wrap up a routine victory.

"I don't care about performances - a win is a win," said Mardle. "There's a lot of dough up for grabs."

Earlier on Wednesday, Andy "Pie Man" Smith moved into the last 16 with a thrilling 4-3 win over American Ray Carver.

The 38-year-old Warwickshire lumberjack produced a brilliant 136 checkout before closing out the match with double eight.

Smith now plays Warriner-Little, who thrashed Gerry Convery 4-0.