The Championship game was settled by Jack Hobbs's powerful header four minutes before the break.
Here, Sports Mole analyses the match.
On target 6
On target 2
Was the result fair?
Just about, yes. Forest were quick out of the blocks but the majority of the first half was Derby's, apart from the one and only goal. After the break the pace slowed as Forest looked to see out the game, while Derby struggled to break down the home side. Keogh's red card made it even harder for the Rams, who should have been two down when Henderson did not put his penalty near enough to the corner.
Billy Davies's side have played better at home this year but won't mind one bit that Derby dominated the ball for long periods today; the fact that they beat their rivals for the first time in four attempts will do just fine. Apart from Hobbs, Andy Reid was the standout player for the hosts and he might be the best player in the division so far this year. His composure on the ball and eye for passes are two of the main reasons Forest are doing so well.
They passed the ball around just fine in the middle of the park, but Nigel Clough will not be pleased by his side's bluntness in the final third. Chris Martin, Johnny Russell and Jamie Ward never got going, with the latter particularly wasteful in promising situations. The defending that allowed Hobbs a free header was shambolic and might mean extra training in that area this week.
Sports Mole's man of the match
Jack Hobbs: As well as the goal, former Liverpool centre-back Hobbs was a huge presence at the back that meant it took 75 minutes for Derby to have a shot on target.
It was a really bad day at the office for Darius Henderson. Not only did he see his penalty saved by Grant, he also got his entry in for miss of the season by directing a free header from six yards well wide of the goal.
Keogh was flabbergasted when Simon Hooper pointed to the spot but he had little choice as it was a clumsy challenge from the Derby skipper. A yellow card was harsh and maybe a penalty was punishment enough.
Forest: Next up for Forest is a trip to Charlton, who haven't scored in their last two matches, on Tuesday night.
Derby: The Rams, meanwhile, can pick up their first home win by beating Ipswich Town, who haven't won away from home, in midweek.