Liverpool put one foot in next season's Champions League with an emphatic win.
The much-maligned Emile Heskey was one of the stars, setting up Michael Owen for the opener before lashing in Steve Gerrard's near-post cross for a second.
Any hopes of a home comeback were dashed when Kenny Cunningham was sent off for hauling down Gerrard.
And the ever-energetic Gerrard, at his inspirational best again, deservedly got on the scoresheet late in the game after being played in by Danny Murphy.
Birmingham are one of a succession of sides that have held the all-important fourth spot at stages during the season.
But with no wins in seven their progress has slowed just as Liverpool have quickened the pace in the race for fourth.
Gerard Houllier's men now look favourites to qualify for the Champions League, particularly on the evidence of this showing.
The England trio of Owen, Heskey and Gerrard are firing on all cylinders and an iron defence has not conceded in 387 minutes of Premiership football.
The hosts were fired up from the off, but having exhibited their steel in the tackle, Liverpool expressed their superiority of technique.
29 mins: Owen outwits Cunningham and Bennett to net
51 mins: Heskey rounds off a quick break with a fierce shot
63 mins: Cunningham is sent off after bringing down Gerrard
86 mins: Gerrard makes it three with a cool finish
Heskey has been linked with a move to St Andrews and showed the locals his Jekyll and Hyde character in the first half.
He failed to either play in Owen or shoot on goal when in a good position, but later linked well with his strike partner in laying on the opening goal.
Heskey controlled a long, flighted pass before threading the ball through to Owen who held off Cunningham before flicking his shot beyond Ian Bennett with a deft touch off the outside of his right boot.
It was a masterclass in forward play which Birmingham's attacking pair of Mikael Forssell and Clinton Morrison tried to emulate, but failed to match.
Forssell was particularly quiet, and although Morrison was on hand to round off a brisk Birmingham passing move, his effort blazed over the bar.
Heskey may be able to give Morrison lessons in finishing in person next term, and he is well placed to do so if his second-half goal is anything to go by.
Owen fed Gerrard who surged down the left before placing a pinpoint cross to the centre which Heskey swept in.
But there was more to Liverpool than their deadly duo upfront, the defence providing a solid platform in front of which Gerrard was dominant.
He grew in stature as the game wore on and when brought down by last defender Cunningham, referee Dunn was left with little choice but to show the red card.
From then on in it was a case of damage limitation for Birmingham, but they were unable to shackle the Reds skipper.
Gerrard played in Owen, who was only denied after a heavy first touch, before finally getting himself on the scoresheet.
The midfielder broke forward again with time running out, acrobatically controlled a Danny Murphy crossfield pass and held off the attentions of Damien Johnson before calmly beating Bennett.
Birmingham: Bennett, Tebily, Cunningham, Upson, Clapham (John 59), Johnson, Savage (Hughes 59), Clemence (Cisse 59), Lazaridis, Forssell, Morrison.
Subs Not Used: Doyle, Martin Taylor.
Sent Off: Cunningham (64).
Booked: Johnson, Cisse.
Liverpool: Dudek, Finnan, Hyypia, Carragher, Riise, Murphy, Gerrard, Hamann, Kewell, Heskey, Owen.
Subs Not Used: Baros, Sinama Pongolle, Biscan, Cheyrou, Luzi Bernardi.
Referee: S Dunn (Gloucestershire).