And nobody will have made a greater impression than Emile Heskey, who performed the remarkable feat for a striker of putting on a match-winning display without getting his name on the score sheet.
But he did everything else. He had one goal-bound effort kicked off the line, laid on two of his side's goals with clever little back heels into the paths of Frank Sinclair and Tony Cottee, and selflessly produced a string of crosses which would have deepened Birmingham's humiliation had his team's finishing been as sharp as his vision.
Trevor Francis, the latest manager to feel the full force of his talents, said: "Heskey is getting better all the time and he is not far from his full England debut. His partnership with Tony Cottee has really developed into something special."
O'Neill agreed. "Heskey has had a really great season for us, but his was one of a number of terrific performances," he said. "Steve Guppy was also top class. He's been forgotten since he made the England B team, but he's playing as well as any left-sided player in the country."
Guppy, who was not averse to switching flanks to torment Birmingham down the right as well, underlined his manager's view with the goal of the game, a swirling right-footed shot from the angle of the penalty area into the far corner of the net.
With Rob Ullathorne matching fellow full-back Sinclair's opening goal seven minutes later, and Leicester's midfield engine room of Neil Lennon and Muzzy Izzet able to turn up the power whenever it was needed, it was an all round performance that gave Birmingham a worrying taste of what to expect if their own upwardly mobile ambitions are realised this season.
The First Division side were never in it, despite pulling a goal back through Steve Robinson when Leicester momentarily took their foot off the throttle after establishing a two-goal lead.
After Cottee and Guppy had restored the balance of power in the second half, Dele Adebola's last-minute strike came as no consolation at all for the Birmingham manager.
"I was aware of the gulf between First Division and Premiership before the game, but I thought our current good form would see us through," Francis said. "But today we came up against a team who work as hard as we do, and on the day the difference in quality was evident."
Goals: Sinclair (20) 1-0; Ullathorne (27) 2-0; Robinson (35) 2-1; Cottee (51) 3-1; Guppy (71) 4-1; Adebola (90) 4-2.
Leicester City (4-4-2): Keller; Sinclair, Elliott, Taggart, Ullathorne; Campbell, Lennon (Zagorakis, 85), Izzet, Guppy; Cottee (Marshall, 72), Heskey. Substitutes not used: Parker, Fenton, Arphexad (gk).
Birmingham City (4-4-2): Poole; Rowett, Ablett, Johnson, Marsh (Grainger h-t); Ndlovu, O'Connor, Robinson, McCarthy (Hughes, 77); Adebola, Furlong (Forster, 63). Substitutes not used: Bennett, Purse.
Referee: U Rennie (Sheffield).
Bookings: Leicester: Cottee.
Man of the match: Heskey.
Attendance: 19,846.Reuse content