The Ulsterman, whose playing days spanned Forest's finest hours, was offered the opportunity to manage them in the spring of 1993, ahead of Clark. He turned it down, preferring to stay at Wycombe Wanderers, whom he had taken from non-League to the Second Division. That he should now be watching their demise from as close a vantage point as Leicester has a certain irony.
O'Neill's rejection suggested to some a lack of ambition but to others wisdom. As a relative rookie in management, he knew he was not ready to step into Brian Clough's shoes.
Within the next two or three weeks, Stuart Pearce, without even the modest experience O'Neill could draw upon then, must indicate whether he is ready to succeed Clark. For him, making the right choice will be tougher still.
Colin Cooper's late header salvaged a draw, giving Forest four points from the matches that preceded and followed the Boxing Day drubbing by Manchester United. But Pearce is under no illusions. "I think to survive we've got to get near to the 46-point mark and as we've only got 14 at present the situation is clearly not good enough," he said.
The Forest board - unsure of its own destiny while take-over manoeuvres continue - has given Pearce a trial period to be determined largely by himself. "The chairman asked me to take over until mid-January and I'll talk it over with my wife then," he said. "I'm a level headed chap, not one to make rash decisions."
O'Neill is not a contender now, having pledged never to follow the lead of Brian Little and Mark McGhee by walking out of Filbert Street with commitments unfulfilled. To lose another manager now would be calamitous for Leicester, clinging to their mid-table perch with a tenuous grip.
Coventry have proved that the difference between comfort and dire straits can be as little as three or four results. O'Neill has conjured from limited resources some splendid results for Leicester, a Boxing Day draw at Liverpool the most recent. But after only one win in seven, he knows such results must come more often.
"After the Liverpool game we had 22 points from 19 games, the half-way point in the season," he said. "We will need at least as many as that in the second half."
Given the lateness of Forest's second equaliser, Saturday's result might appear an opportunity missed. Leicester led twice, in fact, through Emile Heskey's glancing header and some cool finishing by Mustafa Izzet, from a chance made by Heskey. But O'Neill was surprisingly benevolent.
"We were down to the bare bones, with literally only one other player available," he said. "You are disappointed to concede a late goal but the attitude and application was terrific and I can ask for no more."
Pearce, still employing bold tactics, saw glimpses of Forest's old fluidity, their creativity enhanced by the return of Nigel Clough, on loan from Manchester City. Clough scored his first Forest goal since 8 May, 1993, the last day of his father's sad valedictory season. But he should have had a second and it is more vital to Forest even than to Leicester that points come in threes.
Goals: Heskey (10) 1-0; Clough (37) 1-1; Izzet (63) 2-1; Cooper (87) 2-2.
Leicester City (5-4-1): Keller; Grayson, Prior, Hill, Marshall, Lewis (Lawrence, 81); Taylor, Parker, Izzet, Heskey; Claridge. Substitutes not used: Watts, Campbell, Wilson, Poole (gk).
Nottingham Forest (3-4-1-2): Crossley; Blatherwick, Chettle, Pearce; Haland, Cooper, Gemmill (Lyttle, 69), Woan (Allen, 77); Clough; Saunders, Campbell. Substitutes not used: Phillips, Roy, Fettis (gk).
Referee: K Burge (Tonypandy).
Booked: Forest: Chettle, Blatherwick.
Man of the match: Clough.