Burton Albion 1-0 Derby County
Jackson Irvine scored the only goal of the game as Burton Albion beat Derby County in the first competitive match between the near neighbours.
Irvine stooped to meet a Lucas Akins cross to head Burton ahead, while Derby struggled to create a meaningful effort in reply before the break.
Derby substitute Abdoul Camara provided a spark and saw a deflected shot saved at the near post.
Will Hughes fired over the bar late on for the Rams but Burton held on to win.
While just 12 miles of the A38 separate the two sides, the clubs have never featured in the same division - with Burton finishing fifth in the Conference in 2007-08 when Derby County last featured in the Premier League.
The Rams have since remained in England's second tier as Burton have won three promotions in eight years to join them in the Championship for the first time.
Boss Nigel Clough, who left then non-League side Burton to take charge of Derby in 2009, returned to the East Staffordshire club for a second spell last season and guided the Brewers to victory in his first match against the Rams since being sacked by Derby in September 2013.
Burton attacked with greater intent for much of the first half, with Lloyd Dyer, Tom Naylor and Akins - who set Irvine up for the opening goal - menacing throughout.
Jacob Butterfield hit Derby's first shot on target in the 27th minute before John Brayford - making his first appearance for Burton for eight years - blocked a drilled effort from Chris Martin.
Burton also gave new arrival Shaun Barker an emotional debut as the former Derby captain made a first competitive appearance in almost four-and-a-half years against the club that released him last year.
Burton Albion boss Nigel Clough told BBC Radio Derby: "These are the sorts of games that as players you look forward to.
"It's three points on the board and now we need another 43 and not 46 like we did at the start of night. We have a hard eight or nine months ahead of us.
"All we are trying to do is get 15, 16 or however many good lads, working their socks off because that is how we will stay in this league."
Derby County boss Nigel Pearson told BBC Radio Derby: "The levels of performance tonight is not what we are looking for, they are not good enough and not consistent enough.
"I accept we have players out of form and who are struggling to deal with game situations, but we have to work our way through that. There are no shortcuts to it and dealing with the responsibility or dealing with level of hard work we have to put in.
"We have players that need to be in a better place in physical conditioning and we also need to show more resilience collectively."
- 6TurnerBooked at 89mins
- 15NaylorSubstituted forWilliamsonat 87'minutes
- 16PalmerSubstituted forBarkerat 90+3'minutes
- 18MillerSubstituted forMyers-Harnessat 54'minutes
- 10InceSubstituted forCamaraat 45'minutes
- 4BrysonBooked at 78mins
- 18ButterfieldSubstituted forWilsonat 56'minutes
- 9MartinSubstituted forBentat 56'minutes
- Andy Davies
- Shots on Target