Although Dennis Taylor's victory the previous year had been an extraordinary story, Joe Johnson's 1986 triumph was, in many ways, even more remarkable.
Johnson surprised Davis and many others
Johnson, the world no.16 when the championship began, was quoted at 150-1 for the title, not unduly generous odds given that he had failed to win a tournament in seven years as a professional.
But Johnson grew in strength as the championship progressed and seemed to have unshakeable confidence after coming from 12-9 down to beat Terry Griffiths 13-12 in the quarter-finals, his 52 minutes four frame winning streak highlighted by breaks of 102 and 110.
A 16-8 victory over Tony Knowles put him in the final but Steve Davis, attempting to exorcise the ghosts of the previous year, had barely been tested in coming through the other half and was again expected to prevail.
From 8-8 at the end of the first day, Johnson claimed a 13-11 lead going into the final session.
Still, many believed Davis would turn it around but no comeback was forthcoming and Johnson seemed to play without nerves in clinching an 18-12 victory. He remains the Crucible's most unlikely winner.
Mike Hallett had sent Taylor crashing 10-6 in the first round and 17-year-old Stephen Hendry, making his first appearance at the Crucible, was beaten 10-8 by Willie Thorne.