Swine flu has not provoked widespread panic and hysteria in Blackburn. “Five-two, and we’ve got the flu” sang Rovers’ supporters at Ewood Park as Sam Allardyce’s team overcame illness to several players and staff to secure their place in the last eight of the Carling Cup.

The margin of defeat was harsh on Darren Ferguson’s Peterborough, who had their goalkeeper Joe Lewis dismissed shortly before half-time, but Blackburn were ultimately ruthless against 10 men.

Despite making seven changes to the team annihilated at Chelsea on Saturday Allardyce opted for an insurance policy of a strong substitutes’ bench. Among them sat David Dunn, one of the three Blackburn players suspected of contracting swine flu but deemed fit enough for selection here. His fellow substitutes must have been delighted.

The insurance was to prove unnecessary for Blackburn en route to a third quarter-final appearance in three seasons, although not as a result of Peterborough’s performance but the misfortune that conspired against the Championship strugglers. The visitors, 21st in the Championship after two successive promotions under Ferguson, were given an immediate hurdle when Morten Gamst Pedersen swept a superb free-kick into the top corner of Joe Lewis’ goal from 25 yards in the fourth minute. Yet they recovered impressively, with the pace of their strikers Aaron McLean and Shaun Batt plus quality supply from both flanks forcing Blackburn’s makeshift defence into a retreat.

Peterborough deservedly drew level in the 17th minute when the coveted George Boyd won possession in the Rovers area and the full-back Tommy Rowe eventually took over on the left. Rowe sent a tempting cross to the back post and Chris Whelpdale headed across Jason Brown and in via a deflection. Though Nikola Kalinic headed onto the crossbar from close range for Blackburn, the visitors continued to threaten. But luck was not on the side of the underdogs.

Charlie Lee, the United right-back, was felled by a poor, late and unpunished challenge by Martin Olsson a minute before Peterborough’s equaliser and soldiered on until another blow forced his withdrawal. Lee’s replacement, Russell Martin, was only in the fray for seven minutes when he sent a dreadful header intended for his goalkeeper straight to the feet of Pedersen. Lewis tripped the Norwegian and the referee Anthony Taylor pointed to the spot and produced a red card.

Steven Reid, on his first home start of the season, converted as he slipped from 12 yards to prove recent reports of his demise by the Ireland manager Giovanni Trapattoni had been greatly exaggerated.

The 10 men did not go quietly. Four minutes after the restart an incisive counter-attack prised open the Rovers defence and enabled Boyd to enhance his reputation with a devastating finish into the top corner from 18 yards. Only then did the Premier League team begin to stir.

Michel Salgado put Rovers ahead for a third time when he sprinted in behind the visiting defence to meet Brett Emerton’s lofted pass and beat the substitute goalkeeper, James McKeown. The home side spurned numerous chances to increase Ferguson’s misery, with Pedersen culpable of missing an open goal from three yards, and it was only when Kalinic hit a purple patch that their passage was secured. The young striker produced an outstanding turn on the halfway line before playing Benni McCarthy through for an assured finish. He then scored Rovers’ second penalty after Krystian Pearce handled Olsson’s cross.

Carling CupBlackburn RoversPeterboroughAndy Hunterguardian.co.uk