DEFENSIVE frailties sentenced the below-par Baggies to a third successive defeat in a game which saw both teams finish with ten men.
Jerome Thomas' 17th-minute equaliser cancelled out Nikola Kalinic's opener and appeared to set up the second half nicely.
But the Baggies found themselves 3-1 down just past the hour mark as Kalinic and Mame Biram Diouf helped themselves to headed goals from Rover corners.
Kalinic's afternoon proved bitter sweet as he was sent off a minute after his side's third for a late lunge on Paul Scharner.
From that moment on, Blackburn camped in their own half but Albion could not breach their stubborn resistance.
And the hosts' misery was complete three minutes from time when Gabriel Tamas was dismissed for scything down Mame Biram Diouf as he raced towards goal.
The two teams could not have been any closer in the table before kick-off, with Albion starting the day in 12th - one position above Rovers on goal difference.
Nicky Shorey was handed his first league start in six games as Roberto Di Matteo made two changes. The former Villa man replaced the benched Marek Cech at left-back while Thomas, who had recovered from illness, replaced the suspended Chris Brunt.
New Rovers boss Steve Kean made one change, with El Hadji Diouf coming in for Gael Givet.
And the visitors were celebrating with less than three minutes on the clock.
Albion made a sluggish start and were caught napping when Morten Gamst Pedersen hoisted the ball into the left-hand channel.
Kalinic raced clear before beating Scott Carson with a well-placed right-footed shot from 15 yards.
Albion were stung into action by the early setback and Thomas was unlucky to see his 20-yard drive deflect off team-mate Youssouf Mulumbu and screw wide.
The Baggies should have been level on nine minutes when slick play by Gonzalo Jara and Peter Odemwingie put Graham Dorrans through on goal.
The Scotland international looked certain to score as he pulled the trigger, only for Paul Robinson to deny him with a fine reflex save low to his right.
Shorey poured forward in the 15th minute but he also saw a team-mate get in the way of a goalbound effort. This time it was Odemwingie.
But despite all of Albion's pressure, they looked fragile at the back and had a real let off on 16.
Scharner could only divert Michel Salgado's cross into the path of David Dunn who fed Kalinic in the box and the Croatian fired just over from 15 yards.
Back came Albion and James Morrison beat Robinson all ends up with a 30-yard pile-driver, only for his stunning effort to fade away at the last second and curl an inch the wrong side of the left-hand post.
But Albion were deservedly level on 17.
Morrison spearheaded a terrific counter-attack before feeding Somen Tchoyi on the right and his inch-perfect, first-time cross was swept home by Thomas at the far post.
Albion continued to boss the game, although Rovers managed to stem the flow of Baggies chances until the 32nd minute.
After a neat spell of possession, Thomas exchanged a one-two with Morrison on the edge of the Blackburn box before curling a right-footed shot just wide of the far post.
However, when Rovers did attack, Albion still looked shaky and Scharner had to produce a vital headed clearance to deny Mame Biram Diouf a simple chance from Martin Olsson's deflected cross.
Albion threatened one last time before the break, when a Dorrans free-kick into the box ricocheted off two Rovers players and, fortunately for the visitors, bounced to safety.
Rovers were forced to make a change at half-time. Keeper Robinson, who had looked uncomfortable throughout the first-half after requiring treatment during the pre-match warm-up, was replaced by Mark Bunn.
Albion started the second half brightly and Bunn was soon called into action, beating away a fierce near-post drive from Odemwingie, who had raced onto Dorrans' slide-rule pass.
Then, for the first time in the game, Rovers put the Baggies goal under concerted pressure, winning three corners in quick succession.
And, from the last one in the 54th minute, they were back in front.
Pedersen's deep centre was headed back across goal by Ryan Nelsen and Kalinic leapt highest to nod home from two yards.
It was a real kick in the teeth for the hosts and Dorrans failed to trouble Bunn's goal with a right-footed free-kick five minutes later.
However, Albion almost gifted Rovers a third on 59 when Carson, in trying to play the ball back to Tamas, miscued straight to Kalinic. Luckily for the Baggies skipper, the ball ricocheted off the Blackburn striker's leg and straight back into his very grateful arms.
But Albion weren't so lucky on 63.
The Baggies again fell asleep at a Rovers corner, which El Hadji Diouf collected from Pedersen before whipping in a terrific centre and Mame Biram Diouf stooped to head home inside the six-yard box.
But Albion had renewed hope within a minute when dangerman Kalinic was shown a straight red card for a late lunge on Scharner.
The Baggies almost pulled a goal back on 74 when Tchoyi's low cross was nudged by Odemwingie into sub Simon Cox's path and his instinctive prod was brilliantly kept out by Bunn.
Cox pounced on the rebound but saw his close-range header cannon into the ground and loop agonisingly over.
Albion kept plugging away but to no avail, with Cox shooting wide from fellow sub Giles Barnes' lay-off.
From a rare Blackburn attack, Mame Biram Diouf managed to outmuscle Scharner and race into the box, but Carson was equal to his acute drive.
Albion's agony was complete when Scharner headed Dorrans' free-kick against the bar.
To compound matters, Tamas was red-carded three minutes from time for hauling down Mame Biram Diouf as he raced goalwards.
In stoppage time, Thomas's goalbound strike was blocked by Nelsen before Bunn dived to his right to keep out Barnes' header from Dorrans' corner.
Referee Phil Dowd's final whistle moments later brought an end to a thoroughly frustrating afternoon for the Baggies.
ALBION (4-2-3-1): Carson; Jara (Barnes 74), Scharner, Tamas, Shorey; Mulumbu, Dorrans; Tchoyi, Morrison (Cox 66), Thomas; Odemwingie. Subs not used: Myhill (gk), Miller, S Reid, Ibanez, Cech.
BLACKBURN (4-4-2): Robinson (Bunn 46); Salgado (Hoillet 52), Nelsen, Hanley, Olsson; E Diouf (Benjani 81), Dunn, Pedersen, Emerton; Kalinic, M Diouf. Subs not used: Givet, Linganzi, Doran, Morris.
GOALS: ALBION - Thomas (17). BLACKBURN -Kalinic (3, 54), M Diouf (63).
BOOKINGS: ALBION - Jara (foul 19). BLACKBURN - Salgado (foul 44), E Diouf (simulation 71), Bunn (time-wasting 77).
RED CARDS: ALBION - Tamas (serious foul play 87). BLACKBURN - Kalinic (serious foul play 64).
REFEREE: P Dowd (Staffordshire).
ALBION STARMAN: Youssouf Mulumbu.PIC: LEVEL HEADED...Odemwingie congratulates Thomas after his equaliser