The pressure increased on Sheffield Wednesday head coach Carlos Carvalhal after his team were beaten 2-0 at Derby and had skipper Glenn Loovens sent off.
Wednesday have now won only one of their last six games and they were struggling from the moment Loovens brought down Matej Vydra who scored from the penalty spot in the fifth minute.
At least Wednesday showed spirit and stayed in the match until the 86th minute when substitute Bradley Johnson sealed Derby's victory.
Derby stuck with the team that beat Nottingham Forest on Sunday but Wednesday made three changes from the defeat at Bolton, with Kieren Westwood returning in goal.
Vydra scored after 24 seconds against Forest and he was involved in another dramatic start when he burst into the box in the fourth minute and was fouled by Loovens who was shown a red card by referee Scott Duncan.
Vydra then sent Westwood the wrong way with the penalty to leave 10 man Wednesday in serious trouble on a ground where they had not won in almost 12 years.
It nearly got worse for the visitors when Derby broke in the 13th minute with David Nugent playing in Tom Lawrence who lifted the ball over Westwood but hit the left post.
Derby got in again minutes later when Westwood came out of his area and just took the ball away from Richard Keogh who protested the keeper had handled.
There was encouragement for Wednesday in the 24th minute when Gary Hooper got in on the right but the angle was tight and Curtis Davies slid in to put the ball behind.
Derby were given another reminder the game was far from over in the 31st minute when Ross Wallace swung over a corner which Steven Fletcher headed down past Scott Carson but the ball bounced just over the angle.
Wednesday had a good shout for a penalty in the 41st minute when Fletcher appeared to be tripped by Craig Forsyth after he got in front of the left back but this time the referee was unmoved.
Johnny Russell forced Westwood into a diving save just before the break only to be booked after the restart for diving but the Scot nearly set up a second with a curling cross that Vydra put wide in the 57th minute.
Westwood denied Russell from close range two minutes later, and Carson turned away a Barry Bannan shot before Chris Martin's flick in the 71st minute was saved by Westwood's right foot.
Derby were far from convincing but after Bannan had gone close from 25 yards, they finally put the game away in the 86th minute when Russell played in Johnson who turned to beat Carson from 10 yards.