Knox was assistant manager of Rangers when they faced off against their bitter rivals for the chance to meet Airdrieonians in the 1992 showpiece match.
Top of the Premier Division table at the time and favourites for the match, Rangers’ chances took a hit when David Robertson was sent off early in the game.
Despite this, Ally McCoist gave Walter Smith’s side the lead before half-time. Knox, though, was still concerned about a second half fightback and approached a rather unusual source for some assistance.
Writing in his autobiography, School of Hard Knox, he wrote: “David Robertson had been sent off after just a handful of minutes for booting Joe Miller up in the air. Ally McCoist scored before half-time - you can still see my celebrations in the YouTube footage - and I knew Celtic would throw everything at us in the second half.
“I went out before the second half kicked off and grabbed one of the ball boys at Hampden. I asked if he was a Rangers fan and he said “yes”. So I gave him a fiver and told him to get the message round his pals. If the ball went out for a Celtic throw-in, just leave it until the Celtic fans throw it back. If the ball goes out for a Rangers throw-in, just leave it full stop.
“I watched him go round all four sides of the Hampden pitch telling his pals not to go for the ball. We needed every advantage we could get and we managed to hang on for the win.”