Derby 2 (Russell 67, Pearce OG 81) Reading 0
Despite the Rams perhaps having the better of the play, it was Reading who had the best chance of the first half as Jamie Mackie was denied following a one on one with goalkeeper Kelle Roos
Ultimately a fine individual strike from Johnny Russell in the second half, added to an unfortunate Alex Pearce own goal, proved enough for Steve McClaren's men to seal a place in the last sixteen.
Next up a televised home clash with Wolverhampton Wanderers this coming Sunday.
Derby: Roos, Christie, Keogh (C), Shotton, Forsyth, Mascarell, Hughes (Martin 64), Bryson (Eustance 84), Russell, Ibe, Best (Dawkins 77)
Subs not used: Grant, Whitbread, Dawkins, Calero, L Naylor
Reading: Anderson, Gunter (C), Obita, Pearce, Hector (Cooper 87), Guthrie (Taylor 72), Kuhl, Mackie, Edwards, Robson-Kanu (Cox 77), Pogrebnyak
Subs not used: Lincoln, Long, Cooper, Stacey, Blackman
Booked: Robson-Kanu (Simulation 43)
Referee: Simon Hooper
Both sides made changes for the tie - seven for Reading and six for Derby, with Nigel Adkins giving the returning Danny Guthrie and Hal Robson-Kanu their first starts of the campaign.
It was the Rams with early pressure, with full back Cyrus Christie pushing on to cause problems down the right - before Will Hughes fired wide from the opposite flank.
Shortly afterwards Craig Forsyth flicked a header across goal from a corner kick, but thankfully for the Royals nobody could convert from close range.
Leon Best forced a stop from Mikkel Andersen just before the half hour mark, with the Australian stopper palming away a bouncing drive from 25 yards.
The golden chance of the first half would fall to Jamie Mackie - as a disastrous back pass from Christie set the forward one on one with the 'keeper, only for Kelle Roose to pull off a smart save.
Derby still looked dangerous - Will Hughes next to test Andersen, who held comfortably after an effort from just outside the box.
Ryan Edwards then hit a fantastic half volley from outside the area, which dipped towards goal only for Roos to tip over the bar. Goalless it was at the break - Derby the better side, Reading the best chance.
The second period soon exploded into life, as Andersen pulled off a wonderful fingertip save to deny Jordon Ibe, pushing a fizzing shot onto the crossbar. Steve McClaren's men were a real attacking threat - as Russell then curled over from distance.
At the other end a rapid break instigated by Michael Hector ended in some great work by Mackie, whose cross somehow evaded all the on-rushing navy blue shirts - before Robson-Kanu saw a low effort from ten yards saved by Roos.
It was the Rams that took the lead though - an excellent individual effort by Russell, who weaved his way into the box before coolly burying the ball into the bottom right corner.
Pogrebnyak tried to respond immediately as he latched onto Robson-Kanu's lay-off, but blazed off target from 20 yards.
The tie was sealed however with a little under ten minutes remaining on the clock. Martin's cross rebounded off an unfortunate Alex Pearce - rolling past an equally helpless Andersen to put County into the last sixteen.