Steve McClaren's Derby fell to a disappointing 2-0 defeat at second-placed Burnley last weekend, and their task of catching Sean Dyche's men in the Championship table became even more difficult on Saturday.
The deadlock was broken shortly after the hour mark, Steve Morison heading home superbly from Lee Martin's cross.
Richard Keogh had an opportunity to equalise late on, but the centre-back volleyed wide and Derby remain five points adrift of Burnley, who play Blackburn Rovers on Sunday, having now played a game more.
Forest's hopes of climbing into second appear increasingly slim following a 1-0 defeat to struggling Barnsley at Oakwell.
The result represented the perfect tonic for the South Yorkshire outfit, who had lost 5-0 at Huddersfield Town in their last Championship fixture.
Dale Jennings grabbed the only goal of the game, his first for Barnsley.
With an 11-point gap to Burnley, Forest will look to firm up their play-off spot, with seventh-placed Wigan Athletic just three points behind Billy Davies' men with two games in hand.
At Elland Road, resurgent Bolton Wanderers thrashed Leeds United 5-1 to rack up their third straight Championship win.
Dougie Freedman's men were only 1-0 ahead at the break after Joe Mason notched on the stroke of half-time.
Further goals from Lukas Jutkiewicz, Zat Knight, Craig Davies and Andre Moritz put the visitors in dreamland, before Matt Smith notched a consolation in second-half injury time.
Middlesbrough headed into their encounter with Ipswich Town at the Riverside Stadium having failed to register a goal in their last seven league matches.
But a brace from Danny Graham - who was able to celebrate his first Middlesbrough goals for more than nine years after rejoining the club on loan in January - handed Aitor Karanka's men a 2-0 win.
Fourth-placed QPR took advantage of leaders Leicester City and Burnley not being in action by beating Birmingham City 2-0.
On-loan West Ham midfielder Ravel Morrison scored in each half, as QPR's five-match winless run came to an end.
Sheffield Wednesday finished with 10 men as Sam Hutchinson was sent off in a 2-0 defeat at relegation-threatened Yeovil Town, while fellow strugglers Doncaster Rovers were 2-0 victors over Huddersfield Town at the Keepmoat Stadium, with Billy Sharp and David Cotterill bagging for Paul Dickov's charges.
Play-off contenders Brighton and Hove Albion and Reading played out a 1-1 draw at the Amex Stadium, while Blackpool remain in danger following a 1-0 setback at Bournemouth.
Blackpool have taken just four points from their last 17 matches and are winless since the end of November.
