Rovers brushed aside their illness worries to book their place in the last eight of the Carling Cup with a 5-2 win over Peterborough United.
Morten Gamst Pedersen fired the home side in front with a well taken free-kick after just four minutes but Chris Whelpdale levelled on 17 minutes.
The game turned in Rovers' favour when Joe Lewis was sent off after bringing Pedersen down in the box just before the break and Steven Reid converted from the spot.
But despite being a man light Peterborough wouldn't lie down, the Championship side getting back on terms through George Boyd's well struck shot.
Parity was brief however as Michel Salgado grabbed his first English goal soon after.
Goals four and five soon followed. Benni McCarthy slotting home after being set up by Kalinić and the Croatian then added the fifth from the spot after Olsson's centre was handled.
Keith Andrews and Junior Hoilett went close to adding further goals, but Rovers will have been more than satisfied to put their recent problems behind them with a quarter-final draw to look forward to on Saturday.
With all the publicised problems regarding squad selection, Sam Allardyce made seven changes from the side that capitulated at Chelsea at the weekend.
There were first Ewood starts of the season for Phil Jones,Michel Salgado,Brett Emerton,Steven Reid,Jason Brown and Nikola Kalinić who lead the line with Benni McCarthy.
Just four minutes in and Rovers were celebrating the opening goal of the game. Junior Hoilett had been fouled five yards from the edge of the Peterborough box and from the resulting free-kick Morten Gamst Pedersen hit a peach of a shot that flew into the top right corner of Joe Lewis's goal with the England under 21 goalkeeper rooted to the spot.
To their credit the visitors didn't let their heads drop after conceding so early, their pressing game giving Rovers problems.
George Boyd went close to levelling on the quarter hour when his free-kick flew narrowly wide, any touch from the attacking Peterborough players and the ball would have ended up in the net.
But the side from Cambridgeshire were soon celebrating a leveller when just three minutes later a ball from the left by Rowe finds Chris Whelpdale arriving at the back post and he headed past Jason Brown for a deserved equaliser.
On 24 minutes Rovers were very nearly back in front when a centre from Pedersen found Hoilett, he shot into the ground but the high bouncing ball was nodded goalwards by Nikola Kalinić but he was unfortunate to see it bounce off the top of the bar.
The visitors however continued to cause Rovers problems, the home side unable to get their passing game going due to the tenacity of the men in green.
Two minutes from the break Rovers were handed a lifeline and given a man advantage. Steven Reid's ball over the top looked straight forward for Russell Martin but his back header came up short allowing Morten Gamst Pedersen to get to the ball ahead of Lewis who took the Norwegian's legs.
Referee Anthony Taylor had no hesitation in pointing to the spot and issuing a red card for the Peterborough number 1.
Benni McCarthy stood with the ball on the spot whilst Peterborough brought on their replacement goalkeeper, but the South African gave the spot-kick responsibility to Steven Reid and the Republic of Ireland international clipped the ball down the middle past James McKeown who dived in the opposite direction.
It was Reid's first Rovers goal since a header against Chelsea at the end of the 2005/06 season.
On the stroke of half-time Rovers went close to adding a third but from Hoilett's cross Gaël Givet headed straight at McKeown.
The home side started strongly in the opening exchanges of the second half, earning three corners in quick succession. But they couldn't make them count and were made to pay when on 50 minutes a clever pass from Whelpdale found George Boyd in far too much space and he lashed the ball home from the edge of the area to put ten-man Peterborough back in level terms.
Morten Gamst Pedersen then wasted a glorious chance to put Rovers back in the lead when putting Hoilett's centre the wrong side of the post. Then Phil Jones almost capped his Ewood debut with a goal but his downward header from Emerton's centre was saved.
But Rovers kept pressing and probing and got their rewards a minute later. Brett Emerton finding the marauding Michel Salgado in round the back and the former Real Madrid star netted his first goal in English football from close-range.
Steven Reid made way on 70 minutes, the Republic of Ireland coming through his first outing in a month unscathed, David Dunn replacing him to great applause.
Rovers then grabbed two goals in two minutes with strikers Benni McCarthy and Nikola Kalinić helping each other to get on the scoresheet.
It was Kalinić who was the provider for the fourth goal, latching onto Martin Olsson's pass to turn his man on halfway, he then took advantage of a slip from Pearce to race into the opposition half before unselfishly squaring the ball to Benni McCarthy who cooly slotted into the back of the net from the edge of the area, his 50th in a Rovers shirt.
Two minutes later and the roles were reversed. Morten Gamst Pedersen finding Martin Olsson on the overlap and as the Swede crossed the ball struck the arm of the hapless Russell Martin and a second penalty was awarded.
Again Benni McCarthy was first to the ball, but just as the first half he handed the ball to a colleague, this time Nikola Kalinić and the Croatian gleefully accepted with a fired home from the spot sending McKeown the wrong way.
"5-2 and we've got the flu", chanted the home fans.
Rovers could have added further goals to their tally, Keith Andrews and Junior Hoilett going close, but they were happy to settle with their five goals and a place in the quarter-finals of the Carling Cup once again.
ROVERS: Brown; Salgado, Jones, Givet (sub Nelsen 59 mins), Olsson; Hoilett, Reid (sub Dunn 70 mins), Emerton (c) (sub Andrews 78 mins), Pedersen; McCarthy, Kalinić.
Subs not used: Robinson (GK), van Heerden, Jacobsen, Roberts.
PETERBOROUGH: Lewis, Lee (sub Martin 35 mins), Rowe (sub Day 76 mins), Morgan, Pearce, Whelpdale, Diagourana, Frecklington, Boyd, McLean (c), Batt (sub McKeown 44 mins).
Subs not used: Keats, Coutts, Green, Korentang.
Booked: Givet (Rovers)
Off: Lewis (Peterborough)