The duo both picked up injuries in the previous two matches and were replaced at half-time. Speed picked up his calf injury in last week's game with Southampton, while Naysmith was replaced by Sun Jihai on Saturday when he suffered a groin injury.
Meanwhile James Beattie should be fit enough despite coming off midway through the 2nd half against Preston. Matt Kilgallon will serve his last match in his three game ban.
Kevin Blackwell said: "We have a squad of very good players and when someone drops out it is nice to be able to bring someone else of quality in who can do a good job."
In the City camp, Bradley Orr returns from suspension while McAllister and Carey remain unavailable due to their injuries.
If your not attending tonight's game then join us here on Blades Mad for a live match thread. Build-up starts at 7:00pm