Mark Allen won the last four frames to clinch a thrilling 10-9 victory over Matthew Stevens in the first round at the Crucible in Sheffield.
Stevens, who sealed a 10-9 preliminary round win over Fergal O'Brien on a black-ball finish, looked on course for victory after opening a 9-6 lead.
But Allen hit back with a late flurry to make sure of his progression.
Mark Selby is on course for round two after dominating the evening session to lead 8-1 against Jimmy Robertson.
Crucible debutant Robertson won the first frame of the session, but he rarely got a look-in after that as fellow Englishman Selby took firm control of the match by winning eight successive frames.
It was a low-scoring encounter, with Selby's 82 in the final frame of the evening the only break over 50.
Seven-time Crucible champion Stephen Hendry, who has revealed he may quit snooker after the tournament, awaits the winner.
But the majority of the evening session's drama came on the other table, as 2010 quarter-finalist Allen achieved his remarkable comeback.
The Antrim player, who recently revealed he was suffering from depression, came into the session trailing by only a frame at 5-4, but after losing four of the first five frames he found on the brink of a first-round exit.
But he upped his game as Welshman Stevens' performance faltered, beginning his fightback with a break of 103 in the 16th frame, and he finished the match with an inspired run of 45 to set up a second-round clash with Barry Hawkins.