Rob Hulse's header gave Derby the east midlands bragging rights as Nottingham Forest's long unbeaten streak came to a shuddering end following the 1-0 result.
Forest arrived at Pride Park on a 19-game unbeaten league run and looking to rejoin Newcastle at the Coca-Cola Championship summit.
But a tight encounter went the way of the relegation-threatened Rams when Hulse rose to glance home Kris Commons' inswinging free-kick with 12 minutes remaining.
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