In the first half Gallen was the hero turned villain for Plymouth as his spot-kick gave the home side a deserved lead, only for him then to miss a second penalty.

Both sides made a cautious start but it was Plymouth who went close to opening the scoring after five minutes when Scott Sinclair let fly from 25 yards only to be denied by Derby goalkeeper Stephen Bywater, who was alert to the danger and pulled off a cracking save.

Despite Derby currently topping the Coca-Cola Championship table and enjoying a 20-point advantage over their opponents in the league, Plymouth were far from overawed and continued to push for an early breakthrough with a place in the last eight of the FA Cup at stake.

And their efforts were rewarded in controversial fashion after 12 minutes. Gallen went down easily under a challenge from Dean Leacock but, to the fury of the Derby players, referee Mike Dean had no hesitation in pointing to the spot.

Gallen dusted himself down to dispatch the penalty past Bywater despite the keeper getting both hands to the ball and almost keeping it out.

Derby had their first opportunity after 18 minutes, having been awarded a free-kick following a foul by Krisztian Timar on Steven Howard, but David Jones' superb dipping effort from 25 yards flew just over the crossbar.

But it was Plymouth who then twice went desperately close to doubling their advantage with Gallen sending a close-range header inches over and then, just before the half-hour mark, Dan Gosling's piledriver was somehow turned around the post by Bywater.

The goalkeeper's heroics looked to be in vain as Plymouth were awarded a second penalty after 31 minutes when Moore was penalised for hampering Timar. Gallen again stepped up but this time Bywater was equal to the task to keep his side in the tie.

Derby made a double substitution at the start of the second half as they tried to get back into the game with Jon Macken and Giles Barnes coming on for Ryan Smith and Jones respectively.

But it was the home side who continued to threaten with Mo Camara blocking Timar's firmly-struck close-range shot after 54 minutes.

Derby, though, then went agonisingly close to an equaliser when Macken's shot just three minutes later was tipped around over the crossbar by fully-stretched Plymouth goalkeeper Luke McCormick.

However, their hopes of getting back into the tie were extinguished when Moore was booked twice in the space of five minutes for challenges on Lilian Nalis and Gallen and was given his marching orders.

Sinclair's header seven minutes from time, when he got on the end of a David Norris cross, then sealed Plymouth's passage into the quarter-finals of the FA Cup for the first time since 1984.