After Steve Walsh's header late in the first half had cancelled out Kevin Gallacher's excellent opener for Blackburn, neither side could find the stamina to clinch three points and O'Neill joined his opposite number, Brian Kidd, in arguing that to play twice within 48 hours was becoming too much to ask.
"I've been brought up on Christmas programmes like this one but I'm not a player now and the product we are putting out is different from my day," O'Neill said. "Both of us won on Saturday and four points from two games is not a bad haul, but from our point of view it was disappointing not to win tonight.
"It did not really happen for us and we finished pretty tired. Maybe it is time there was a break in the season at some point, for perhaps 16 to 18 days, so that players can recharge."
Blackburn, unbeaten in five matches since Kidd was appointed manager, could be pleased at least to have passed a test of resilience, even though they suffered another injury when Christian Dailly was carried off with a thigh strain that could keep him out for weeks. They are already resigned to losing Chris Sutton for a lengthy period after he was hurt on Saturday. For their part, Leicester lost Robbie Savage after only seven minutes, the Welshman suffering medial ligament damage.
Blackburn's best spell came in the second quarter of the match. First, Jason Wilcox curled a 25-yard free-kick around the Leicester wall that had Kasey Keller diving at full stretch to his right to save. Moments later, a goal-bound strike from Keith Gillespie struck Walsh's body to Leicester's good fortune.
Leicester, for whom Steve Guppy provided a stream of useful crosses, countered with a well-worked corner routine in which John Filan made a brilliant save from Frank Sinclair.
Ten minutes later, Blackburn went ahead through Gallacher, who dispossessed Matt Elliott and then sent the ball curling over Keller's right shoulder from 25 yards.
Leicester levelled the score within six minutes, Guppy again supplying the ammunition with a left-wing corner that Walsh, at the near post, powered home.
In the second half, a deflected shot by Neil Lennon rebounded off the Blackburn crossbar, but Leicester could not find the legs to secure a winning advantage.
Goals: Gallacher (38) 0-1; Walsh (44) 1-1.
Leicester City (4-4-2): Keller; Sinclair, Elliott, Walsh, Ullathorne; Savage (Zagorakis, 7; Marshall, 72), Lennon, Izzet, Guppy; Heskey, Cottee. Substitutes not used: Taggart, Fenton, Arphexad (gk).
Blackburn Rovers (4-4-2): Filan; Kenna, Peacock, Dailly (Broomes, 19), Davidson; Gillespie, McKinlay, Sherwood, Wilcox; Gallacher, Davies. Substitutes not used: Duff, Johnson, Croft, Fettis (gk).
Referee: A Wilkie (Chester-le-Street).
Bookings: Leicester: Zagorakis, Elliott; Blackburn: Peacock.
Man of the match: Guppy.