Jack Lisowski created a major upset as he defeated world number two Mark Selby 4-3 in the opening round of the PTC Grand Finals in Galway.

There was never more than a frame between Lisowski, ranked 42nd in the world, and Selby as the game went to a decider, the 21-year-old top-scoring with a 96 break in frame five.

That put him 3-2 ahead and, though Selby levelled with a 63 in the next, Lisowski came out on top in a scrappy final frame to seal a last-16 clash with Tom Ford.

Joe Swail hit back from 3-0 down to stun world number six Stephen Maguire by reeling off four frames in a row.

Maguire looked set for a comfortable evening's work after rattling in breaks of 89, 56 and 52 to move within one frame of victory but Swail nicked the fourth.

The Scot had a golden opportunity to wrap up the match in the fifth frame but missed a regulation black off the last red and his 43-year-old opponent moved to within one behind.

A break of 69 levelled matters and the Northern Irishman sealed a shock victory after two visits to the table.

"If you look at my track record you know that I don't give in. No matter how bad things are I always stick at it. I've practised a lot over the last few days and this is the result," Swail told worldsnooker.com

The 43-year-old dropped off the main tour last season and had to qualify for this event as an amateur.

He added: "I haven't had much to shout about over the last few years, it has been tough.

"I knew things would turn around on and off the table. I knew sooner or later it would come, but what a way for it to come here, beating one of the top players from 3-0 down. I'm absolutely over the moon."

Swail will next face compatriot Mark Allen, who thrashed Mark Davis 4-0.

Allen looked in formidable form as he bids to win back-to-back events, having retained his Haikou World Open crown earlier this month.

Neil Robertson was given a scare before he saw off Jamie Burnett 4-2.

The 2010 world champion trailed 2-0, but stormed back to take four consecutive frames - the last off a re-spotted black - to progress.

Barry Hawkins breezed past Li Hang 4-0, while Martin Gould crashed out after a 4-2 defeat to lower-ranked Ford.