Wayne Rooney's first game as figurehead of Derby's new coaching team ended in a 1-0 Sky Bet Championship defeat to Bristol City at Ashton Gate.
Substitute Famara Diedhiou struck the only goal on 78 minutes, latching onto an Antoine Semenyo cross from the right and beating David Marshall with a low left-footed shot from 12 yards.
It was enough to settle a game of few chances and keep Derby pinned to the bottom of the table, while the hosts kept themselves flying high among the frontrunners.
Rooney played the whole game but was unable to inspire his side to victory against a well-organised home defence.
Derby's four-man coaching team, including former Bristol City player Liam Rosenior, who directed operations from the dugout, made three changes from the 2-0 home defeat by Barnsley, calling Andre Wisdom, Max Bird and Duane Holmes into a 4-2-3-1 formation.
Bristol, whose training ground only reopened on Thursday after a Covid-19 outbreak, were unchanged from their 1-0 victory at Cardiff last time out.
It took an outstanding Dan Bentley save to stop Derby taking a sixth-minute lead. The goalkeeper arched his back to tip over a well-struck Martyn Waghorn volley from the edge of the box.
Five minutes later, Marshall was almost left red-faced when robbed by Jamie Paterson, but the City player seemed more surprised than anyone and a poor touch allowed the goalkeeper to recover.
Both sides settled into playing neat passing football without an end product. The game was past the half-hour mark when Semenyo forced a save from Marshall with a low drive.
At the other end, Bentley was relieved to see a deflected shot from Holmes go wide. The busy Holmes then put Jason Knight in on the right, but his cross was blocked by Tomas Kalas.
Bristol had the first meaningful goal attempt of the second half as Semenyo's 59th-minute chance was dealt with by Marshall at his near post. Seconds later, Waghorn was just wide for Derby with a curling effort.
Semenyo headed wide from a Jack Hunt cross as both teams again attacked with promise. Holmes fired over for the visitors before Paterson wasted a good Bristol chance by shooting over from inside the box.
Both sides made changes, Bristol head coach Dean Holden sending on Diedhiou and Chris Brunt for Martin and Callum O'Dowda before Derby responded by replacing Holmes with Morgan Whittaker.
It was Diedhiou's introduction that reaped dividends. More changes followed for both sides, but while Derby threw men forward in the closing stages their finishing was not accurate enough to test Bentley.
Matt Clarke was wide with a header as the hosts soaked up late pressure to claim the points.
What the managers said...
Bristol City's Dean Holden: "To play like that after only one and a half day's training this week was an unbelievable effort by the players. I can't stress too much how well they did in the circumstances. During an international break you normally have two weeks to build up to the next game.
"There was concern about the health of many players and staff, but they all responded professionally and the team looked solid and well-organised throughout the game."
Derby coach Liam Rosenior: "The players gave us everything and we are proud of them. Apart from the goal, I don't think Bristol created a worthwhile chance. We may not have had too many clear openings ourselves but we got the ball into dangerous areas on countless occasions and had two good penalty shouts.
"Those are things we cannot control. Rather than feeling that luck turns against you when you are bottom of the table, we want the players to take responsibility for the things they can affect. That will be the message when we play Middlesbrough in our next game. But I am not going to have a go at any of the lads today because they all were fully committed and tried their hardest."
"It was a proud day for me directing things from the dugout for the first time. At one point I passed a slip of paper to Wayne because I felt we needed to change formation and he passed the message on. He showed again what a great player he still is. But it is not about me or him at the moment, it is about four of us doing our utmost to bring the best out of the lads. We all have an equal say and that will continue. We have some very good players to work with, which is very important, and there were plenty of positives this afternoon."