Oliver Norwood, a £1.2million buy from Town in August, threaded the ball through for substitute Blackman to drill Reading into the fourth round and settle a largely disappointing game.
The first shot at goal did not arrive until first-half stoppage-time – and Norwood blasted high and wide from 35 yards. Until then the game was a dour affair dominated by Reading’s delaying and spoiling tactics.
Frontman James Vaughan, reportedly a transfer target for Barclays Premier League Burnley, nearly sparked the game into life on 28 minutes – but Alex Pearce cleared his long punt forward just as Nahki Wells was about to pounce in the six-yard area.
The best action came in the 40th minute when Vaughan tussled with Royals keeper Mikkel Andersen for a free-kick. Tommy Smith was fouled by Hal Robson-Kanu and when Conor Coady’s cleared set-piece was lofted back into the box by Jonathan Hogg the pair clashed. The ball ran loose and was eventually cleared – but referee Philip Gibbs had already given a foul against Vaughan.
Reading’s Jamie Mackie was substituted at half-time with the threat of a red card hanging over the on-loan Nottingham Forest striker, who was booked in the 16th minute for a foul on Harry Bunn and then warned by referee Phil Gibbs for a late lunge on Hogg in the 36th minute. The Scotland cap pushed his luck further by appearing to argue with the referee as the teams went off at half-time.
There was little increase in urgency after the break, although Vaughan did his best to inspire things when he headed over from close range on the hour following Jack Robinson’s cross from the left.
Wells and substitute Sean Scannell went close after Mackie’s replacement, Blackman, had made the decisive breakthrough with the first shot on target of the match.
Bunn’s surge into the box in the 76th minute was ended by Chris Gunter but Gibbs ruled no penalty. The Royals’ players surrounded Bunn and Wells had to pull the youngster away from the confrontation.
Wells then hit the near post side-netting with a cheeky flick from Coady’s low corner from the left, before a frustrated Hogg was sent off in stoppage-time after a melee. Danny Williams committed a foul and walked off with the ball, Hogg tried to get it off him and the pair appeared to trade blows, with Williams booked and Hogg picking up a second yellow.
That proved to be the last action of a poor match which marked Steve Clarke’s second win as Reading boss.