Mr Rennie thus achieved the rare distinction of being jeered off by both sets of supporters, the home fans no doubt believing that the five Blackburn names in his notebook represented an unfair allocation of blame for the game's numerous clumsy clashes and collisions.
The roll call began with Garry Flitcroft after a mere 15 seconds and ended with Emile Heskey and Frank Sinclair in the last few minutes. In between, Blackburn also had Chris Sutton, Sebastien Perez, Darren Peacock and Tim Flowers booked for various offences. Rovers' manager Roy Hodgson, later called Mr Rennie's performance "lamentable". Although he claimed not to want even to discuss the referee, he added: "If he had awarded that penalty it would have been the ice cream on the dessert."
The incident in question saw Steve Walsh apparently bundled over by Tim Sherwood, but a penalty and a draw would not truly have represented Leicester's just desserts.
After excellent form in their first two matches, they lacked, by Martin O'Neill's admission, the same qualities yesterday and came close to being comprehensively outplayed in the first half. Blackburn could have had more than their single goal, swept in by Gallacher after Flitcroft had got a touch to Damien Duff's left-wing cross in the 13th minute. The old firm of Gallacher and Sutton always looked dangerous and it took fine saves from Kasey Keller to prevent Gallacher and Flitcroft from extending the lead.
All of that must have made sobering viewing for Blackburn's record signing Kevin Davies, relegated to the bench yesterday until the last 10 minutes. With Christian Dailly also awaiting a late introduction into the game, it made for an expensive set of substitutes, although reuniting Gallacher and Sutton gave Rovers the cutting edge that they have so badly lacked of late.
"The fact is that we brought in Kevin Davies to compliment our strike force, not necessarily to replace anyone," said Hodgson of his obvious dilemma. "It's a long season and if the others play well enough to keep him out of the side it will be money well spent." The era of the pounds 7.5m gee-up has arrived, it seems.
Blackburn still showed enough of their ring rust in front of goal to leave Leicester in with a chance that they hardly deserved. Some hesitancy was shown in a defence generally well marshalled when Stephane Henchoz allowed both Heskey and Tony Cottee glimpses of goal as Rovers lost their way in the latter stages. "We might have got something at the end - a few scraps," said O'Neill. "But the Premiership is too demanding to take 25 minutes off in a game. We were nothing like our normal selves."