Rob Hulse's powerful header earned Derby a 1-0 victory over Charlton which ensured their Coca-Cola Championship status.
Hulse, who was named Derby's player of the year before kick-off, converted Barry Bannan's header back across goal after 70 minutes for the only goal of a scrappy encounter at Pride Park.
There were few chances in a dour first half, with Martin Albrechtsen heading Derby's only on-target effort, while Kris Commons twice shot wide from long range.
Nick Bailey, Charlton's top scorer with 12 goals this season, had two shots from distance for the visitors but both failed to trouble Rams goalkeeper Stephen Bywater.
Hulse went close with two headers from set pieces early in the second period before heading Derby in front after Charlton failed to clear.
It was the former Sheffield United striker's 18th of the season, securing the Rams' ninth win at Pride Park this term and meaning they avoid a final-day battle against joining Charlton in dropping to League One.
Nigel Clough succeeded Paul Jewell as Derby boss on January 6 with the Rams having won once in the previous nine games, but their battle against relegation continued.
Clough's side had lost their last three and were five points clear of the drop zone with two matches remaining entering the penultimate fixture of the season.
Charlton, who were finally relegated following last Saturday's draw with Blackpool, had recovered their resilience but were still struggling to triumph after one win in an unbeaten run of six matches entering the game.
The hosts began the better, but it took 13 minutes before the first effort on goal was registered, with Albrechtsen heading Gary Teale's corner straight at Charlton goalkeeper Rob Elliot.
Teale's fellow Scotland international Commons shot wide from 25 yards and Jonjo Shelvey's delivery failed him as Charlton had a set-piece opportunity at the other end.
Commons mis-hit a left-foot shot from long range as Derby again failed to test Elliot.
Bywater, previously a spectator, was called into action twice in quick succession by Bailey.
However, both of the Charlton midfielder's efforts from 30 yards were held comfortably by the Rams stopper as the half ended goalless.
Hulse saw his second-half header from on loan Aston Villa midfielder Bannan's corner tipped over by Elliot before missing the target from Teale's corner kick shortly afterwards.
Albrechtsen headed wide from another Teale set piece before Mark Hudson headed over for Charlton from Shelvey's corner.
Zheng Zhi twice shot wide from long distance before Hulse struck at the other end.
Charlton defender Kelly Youga failed to clear Teale's corner and the diminutive Bannan headed back across the area for Hulse to power in his effort into the top corner.
Shelvey twice had efforts off target and substitute Tresor Kandol missed from 12 yards, while Commons shot over at the other end.
Hulse missed the opportunity to add a second from 12 yards after 86 minutes but Derby triumphed.
Teams:
Derby Bywater, Connolly, Albrechtsen, Nyatanga, Stewart, Varney (Pearson 69), Savage (Eustace 79),Bannan (Sterjovski 88), Teale, Commons, Hulse.
Subs Not Used: Carroll, Villa.
Booked: Commons.
Goals: Hulse 70.
Charlton Elliot, Butterfield, Ward (Wagstaff 82), Hudson, Youga, Sam, Racon, Zhi (Kandol 72), Bailey, Shelvey, Burton.
Subs Not Used: Randolph, Spring, Solly.
Booked: Bailey.
Att: 31,541
Ref: Fred Graham (Essex).