IT may have been hard to tell from the swathes of empty seats around the ground but the fabled magic of the FA Cup was alive and well at Ewood Park on Saturday.

If not off the pitch then certainly on it as Gary Bowyer’s Championship side set the ball rolling on a genuinely thrilling afternoon of upsets.

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It is a shame, then, that there were not more home supporters there to see the Premier League Swans sent crashing out.

Pundits were quick to stick the boot in to Rovers’ second lowest FA Cup crowd for 36 years but they did so without asking why.

Poor league form was one factor, so too the atmosphere-sapping early kick-off time.

But the bigger aspects were the fact that the tie was shown live through Sky TV and, by Rovers’ standards, the high ticket prices.

It is hard to castigate a club that is committed to offering its supporters affordable league football.

But on this occasion, at a time of year when most people are feeling the pinch, its decision to charge £20 for adults backfired.

Every credit, then, to the 5,338 Rovers fans who handed over their hard-earned on the turnstiles.

They were rewarded with as good a performance as they have seen from their team all season.

If Lady Luck deserted Rovers against Wigan Athletic one week earlier then she was smiling here.

Both managers agreed afterwards the decision to send off Kyle Bartley for a professional foul on Josh King just seven minutes into the contest was harsh.

But the reason why Bartley found himself in a position to be dismissed was a direct result of Rovers boss Bowyer’s decision to deploy King as a lone striker.

Eyebrows were raised before kick-off when his line-up, minus top-scorers Rudy Gestede, Jordan Rhodes and Ben Marshall, was released.

But if ever there was a classic case of waiting until after a match before criticising then this was it as Bowyer ultimately got his selection and tactics absolutely spot-on.

So much so that he must now give careful consideration to how many changes he makes for tomorrow’s trip to Derby County.

He has posers all over the pitch not least in the centre of defence, where Shane Duffy and Matt Kilgallon formed a formidable partnership in the absence of captain Grant Hanley, and up front, where King ran Swansea ragged for 60 minutes before being replaced by Gestede.

It appeared a questionable call at the time but with Garry Monk’s 10 men defending deeper and deeper, so threatened were they by the Norwegian’s pace, it proved totally the correct one.

As within 18 minutes of his arrival Gestede had marked his first appearance since Crystal Palace signalled their intent to sign him by notching his 13th goal of the season.

Given much of the build-up to the fourth-round encounter had centred on his future it would have been fitting had it proved to be the winner.

But in the end it had to settle for being the decisive strike after Craig Conway put a seal on a thoroughly deserved success that should serve as a big confidence boost to Rovers’ flagging play-off hopes.

The gap to the top six now stands at 11 points but even that is not insurmountable if they play as well as they did here.

Despite losing Bartley early on, it was the Swans who went in front in the 21st minute when Gylfi Sigurdsson made stand-in skipper Jason Lowe pay for standing off with a stunning 30-yard strike. But within two minutes Rovers were level thanks to a wonderful team goal.

Conway and King combined to get Markus Olsson in down the left and his hooked cross to the back post was nodded down by Tom Cairney to Chris Taylor.

The two-goal hero of the third-round win at Charlton Athletic still had a lot to do but he showed brilliant technique to bring the ball under his control before spinning and volleying into the net.

That was the way it stayed until the 78th minute when Gestede showed athleticism to stab in from Cairney’s quickly taken short corner.

And the outcome was put beyond doubt in the final minute of normal time when Conway played a one-two with Olsson and saw his 20-yard drive squirm under Lukasz Fabianski.

That was that but there was still time for Swansea to be reduced to nine men, Sigurdsson letting frustration get the better of him with a deliberate lunge at Taylor.