El Karkouri hammered a stunning 25-yard free kick past Blackburn goalkeeper Brad Friedel to snatch all three points after Stephane Henchoz had been booked for holding back substitute Marcus Bent.

It looked like Charlton’s fierce endeavours would go unrewarded despite a plucky showing from a much-changed team following Saturday’s 2-1 defeat at Sheffield United.

Reed dropped Dennis Rommedahl, Darren Ambrose and Matt Holland but found a new hero in striker Lloyd Sam, who should have had a penalty when brought down by Lucas Neill in the first half.

He then missed a sitter from close range but was given a standing ovation when taken off 20 minutes from time.

Sam, 22, whose only previous start was against Hartlepool in the Carling Cup last season, was on loan at Sheffield Wednesday at the start of the campaign but is highly rated by Reed.

He took up a position just behind main striker Darren Bent in a modified version of the manager’s 4-5-1 formation, which had not entirely caught the imagination of the home fans but soon won their support as Sam posed a meaningful threat to the Blackburn goal.

Charlton were convinced he should have had a penalty when Neill’s clumsy-looking challenge from behind sent him tumbling in the 26th minute but referee Chris Foy waved away the home appeals.

Then, four minutes later, the energetic Sam moved in on Bent’s cross from the right – only to sky the chance over the bar from just eight yards under pressure from Neill.

Blackburn were busy early on, looking to follow up their first win in seven league games against Fulham on Saturday, and Morten Gamst Pedersen twice went close from Brett Emerton crosses.

He headed into the side-netting and then found plenty of space in the area for a shot which might have beaten Scott Carson but for Hermann Hreidarsson’s intervention.

It was a significant occasion for the Valley faithful, marking the 14th anniversary of their return to the famous old stadium after Charlton ground-shared with Crystal Palace and West Ham to save the club going bust.

The Addicks were seeking their first win in four games since squeaking through in a penalty shootout at Chesterfield to reach the quarter-finals of the Carling Cup for the first time.

Sam had an early half-chance when Andy Reid played Bent through down the right but could not quite connect with his head to a deep cross.

Carson looked less than secure pawing away a right-wing centre by Brett Emerton soon afterwards and Charlton suffered a setback when Djimi Traore had to be replaced by Souleymane Diawara in the 24th minute.

But they redoubled their efforts and, following Bent’s run and cross from the left, Radostin Kishishev – one of three changes in the starting line-up - latched onto a return pass from Sam and curled his shot just wide from the edge of the area.

It needed a fine tackle by Henchoz soon afterwards to stop Sam breaking through the middle and the youngster was denied his penalty claim before shooting over.

Blackburn finished the half with Benni McCarthy’s header ruled just offside as Carson beat it out. Then Shabani Nonda forced the keeper into a brave close-range save in stoppage-time.

McCarthy missed a good opportunity for Rovers early in the second half after Friedel’s brave save from Bryan Hughes at the other end.

The Dutch striker buried his shot in the side-netting when well placed for Shabani Nonda’s cross.

But Charlton fought bravely to retain the initiative and Hreidarsson missed a great chance, heading Andy Reid’s corner over the bar from six yards before the late drama.