Selby was not at his best in the first-round clash in Preston, but rode his luck before setting up a last-16 clash with Neil Robertson.
“I probably should have lost it,” Selby said afterwards.
“I didn’t expect Jimmy to miss in the final frame and I thought he was going to win it in that visit. I was just happy to get a chance and when I did get one I managed to capitalise.
“Winning breeds confidence and if you aren’t winning then it goes the opposite way and you start doubting yourself, no matter what you have achieved in the past. Sometimes you start questioning yourself and go back to the practice table.”
Meanwhile, Stuart Bingham recorded an impressive 4-2 victory against Mark Williams to book a last-16 clash with Anthony McGill and Ding Junhui eased past Mark King 4-1.
Next up for Ding is Mark Joyce, who hit back from 3-1 down to defeat Kyren Wilson 4-3.