The Reds were 3-0 up at the break courtesy of Radoslaw Majewski's rocket, an own goal by Rob Hulse and a tidy finish from Nathan Tyson.
But two deflected goals early in the second half from Miles Addison and Jake Livermore, his first since joining the Rams on loan from Tottenham, set up a thrilling finale.
However, there was to be no repeat of Derby's thrilling comeback in the FA Cup fourth round last season and Forest held on.
Former Forest winger Kris Commons endured a torrid time on his third return to his old stomping ground.
It was his goal that completed Derby's fightback in the cup in February and he was instrumental as the Rams won once again at the City Ground later that month.
It was a different tale this time round for the Scotland international. He was culpable for two of Forest's goals, conceding a free-kick before giving away the ball with some lackadaisical play midway inside his own half.
Commons was replaced by Lee Croft at the break and Derby were as dominant in the second half as Forest had been in the first period.
Radoslaw Majewski's rocket got the derby off to an explosive start.
The Poland international, who scored the first goal of his loan spell from Groclin against Middlesbrough in midweek to set up a Carling Cup third round clash at home to Blackburn, crashed an unstoppable shot in off the underside of the crossbar after just 58 seconds.
Chris Cohen's long-range shot from the left side narrowly missed the far post after finding a path through a crowded penalty area.
Gary Teale spurned a good chance to bring Derby level midway
through the first half, dragging his shot wide after Hulse's pass found him with time and space on the edge of the area.
It proved to be a costly miss as Forest doubled their lead after 28 minutes.
Commons needlessly brought down Joe Garner on the right touchline and from Cohen's inswinging free-kick the ball ended up in the Derby net.
Dexter Blackstock wheeled away in celebration but the final touch was off Hulse's head.
Hulse thought he had made amends eight minutes later but his close-range header was ruled out by referee Martin Atkinson.
Stephen Pearson then went on a wonderful mazy run and slipped in Hulse behind the Forest defence but Lee Camp was quickly out of his goal to block the shot with his legs.
Just as Derby were showing signs that they could get back into the match, Commons' dallying seemingly put the game beyond them.
He lost possession trying to slip the ball through Paul McKenna's legs and Blackstock put Tyson in the clear to round Stephen Bywater and slot home into an empty net.
Derby were famously 2-0 down at the City Ground in the cup last season but came back to win 3-2.
The 4,376 travelling support thought another stirring comeback was on when Addison and Livermore brought the Rams within a goal their hosts with around half-an-hour remaining.
Paul Connolley's long punt forward was flicked on by Jake Buxton and Addison's overhead kick struck Wes Morgan and wrong-footed Camp as it flew into the net in the 51st minute.
Nine minutes later Livermore's left-foot shot from the edge of the box found its way into the bottom corner after deflecting off Luke Chambers.
Derby's tails were up but as they pushed for an equalising goal Forest almost caught them on the break as Tyson's effort just cleared the crossbar.