Lines, already responsible for one of the biggest shocks of the season so far when he ousted the defending champion John Higgins in the first round, continued to prove a surprise by reaching the quarter-finals.
Lines, who secured his first appearance in the last eight of a world ranking event since he joined the paid ranks in 1991, said: "I can't believe it. This is two steps more than I've ever gone before and I am loving every minute of it."
Ebdon, out of step since he was the runner-up to Stephen Hendry at September's British Open, kept in touch early on by taking two of the opening four frames on the black. Breaks of 37, 32 and 70 then carried Ebdon into a 4-3 lead and, despite sitting out a run of 52 from Lines in the eighth frame, he looked set to claim it. But, needing only the last two colours and with the black a formality, Ebdon blundered by missing a straightforward pink to a top corner pocket.
"I was resigned to losing. I couldn't quite believe what was happening when the pink didn't drop," said Lines, who moved to level the scores at 4-4. Ebdon had the chance to make amends in the decider but he missed a vital pink and Lines eventually cleared from the last red to blue to cause another upset.