He raced ahead in the first frame, and in his second he capitalised on a lucky triple-plant that allowed him to come back from behind into a two-frame lead. That became three when some safety play and attritional approaches left the pair to fight it out on the black, with Ford able to hold his nerve.
Trump then began his fightback, hitting a 104 century in the fourth. A break of 64 in the fifth reduced the deficit to a single frame.
Tom Ford blows 147 chance at World Snooker Championship
Unflustered, Ford answered with a 140 break, the highest of the match and one to double his career centuries at the Crucible.
A break of 61 in the next frame meant that the unfancied player from Leicester had kept the reigning world champion from potting a ball for two consecutive frames.
Showing the determination that brought him a world championship, and some exceptional pre-lockdown form, Trump struck back with two frames, including a hard-fought ninth.
Judd Trump plays three exhibition shots, one right-handed at World Championship
In the afternoon's other game, Ash Carty pulled off a comeback of his own to finish 5-4 down to Stuart Bingham, when it had looked like his opponent would convert a 30-0 lead in the ninth frame into a 6-3 lead.
Meanwhile, the second evening match saw Alan McManus assume a 5-4 lead over fellow vetaran Mark Williams with the pair locked in an enthralling battle.