Christophe Dugarry was sent off as Birmingham's alarming dip in form continued with four goals in 22 second half minutes – ending a run of five successive away defeats for Graeme Souness' side.
Dugarry may have been fortunate to stay on the pitch in the first half after appearing to catch Craig Short in the face with his arm.
But two bookings in the space of eight minutes midway through the second period – for dissent and then an off the ball incident in the Rovers penalty area – led to him being dismissed by referee Graham Barber.
His red card immediately followed on from Blackburn's initial double strike from Barry Ferguson and Lucas Neill, with both goals set up by substitute Andy Cole soon after he had replaced Dwight Yorke.
The former England striker produced two telling passes to effectively settle the issue – the like of which had seldom been seen beforehand in a match of plenty of needle and commitment but little quality.
Souness will not care about that as his side collected three precious points in their battle to move away from the Barclaycard Premiership relegation zone.
But Blues are in freefall after their early season lofty placing of fourth – they have now managed just one win and six points from their last nine games.
Brett Emerton, who had scored in Rovers win against Tottenham last weekend, was the first player to threaten to break the deadlock.
He found himself in space on the right side of the Blues penalty area after being put through by Ferguson but his cross–cum–shot eluded everyone – including the advancing Yorke.
When City retaliated Stan Lazaridis was unable to keep down his header from a teasing cross by the recalled Jeff Kenna, which bounced awkwardly just before the Australian winger made contact.
Rovers defender Craig Short was unhappy after taking a knock in the mouth during a challenge from Christophe Dugarry and he needed touchline treatment.
Dugarry, who had come in for rough treatment in last season's match at Ewood Park, also escaped punishment from Barber after a clumsy looking challenge on Vratislav Gresko.
Short took some retribution on Dugarry after their earlier spat to leave the City striker on the floor and both players were severely spoken to by Barber.
Maik Taylor went down onto his knees to comfortably clutch a shot from out on the right flank from Emerton while in a Blues counter–attack Forssell sent a looping header from a Lazaridis cross straight at Brad Friedel.
Lazaridis was left poleaxed on the touchline after being on the receiving end of a challenge from Todd – but again Barber took no action.
He finally reached for his notebook after 38 minutes to yellow card Emerton after a foul on Forssell.
In a rare moment of excitement Forssell had a shot on the turn from 20 yards deflected for a corner.
Blues tried to build up some momentum at the start of the second half and Forssell had the ball in the net after 55 minutes.
But Dugarry was clearly climbing all over Short to reach a cross for Lazaridis before the ball broke to the Finnish international – and the effort was ruled out.
Souness decided to replace the ineffective Yorke with Cole, back in the fold after completing a suspension, at the hour mark.
After 63 minutes Taylor produced the first meaningful save of the game to turn aside a header from Emerton following a cross from Gallagher.
But the home side were then stunned as Rovers struck twice in two minutes with Cole the creator on both occasions.
The former Newcastle and Manchester United striker threaded a pass into the path of Ferguson and the Scotland international kept his cool to turn his shot wide of Taylor.
Then it was Cole who put Neill clear – and he hammered a rising shot past Taylor into the roof of the net.
Dugarry was then red–carded and with eight minutes left Tugay made it 3–0 with a stunning 25–yard strike which flew past Taylor.
There was still time for Paul Gallagher to put the icing on the cake with a close range effort in the dying seconds – with St Andrews half empty.
Birmingham City 0 Blackburn Rovers 4
Ferguson 66, Neill 68, Tugay 82, Gallagher 88
Half-time: 0-0 Attendance: 29,354
- More about:
- Birmingham City FC
- Blackburn Rovers
- Premier League
- Sir Alex Ferguson
- St Andrews Stadium
- The Carling Cup
- Tottenham Hotspur