Derby 3-1 Peterborough
Derby preserved their Championship status with a 3-1 win over Peterborough, who remain in trouble.
Relegation-threatened Posh were the form side but conceded to Craig Bryson five minutes before half-time.
Chris Martin and Richard Keogh added to the visitors' woes before Grant McCann scored a consolation penalty following keeper Frank Fielding's dismissal.
The result leaves Darren Ferguson's men a place outside the relegation zone on goal difference alone.
It was Derby who started stronger, with former Posh midfielder Paul Coutts' mishit cross smashing against a post after just two minutes.
The Rams dominated the first half and should have taken the lead earlier but for missed opportunities from Martin, Keogh and Conor Sammon.
But Bryson netted just before the break - leading scorer Jamie Ward and Sammon combining well down the left then picking out the Scotland international to blast the ball home from close range.
After the interval Derby stretched their lead with two goals in three minutes - Martin crashing home a drive then Keogh heading in a third at the far post.
The hosts' day was dampened when, just after the hour, keeper Fielding brought down Dwight Gayle, who was clean through on goal.
The red card for the stopper, and McCann's successful conversion from the spot, made little impact on the final result with Peterborough now facing two crucial games against Sheffield Wednesday and Crystal Palace before the end of the season.
Peterborough manager Darren Ferguson:
"I'm absolutely delighted. We are out of the bottom three which is the best thing that's happened all day.
"Nothing else positive did happen so it's still in our own hands with two games to go and after the start we had to the season, losing our first seven games, I would have taken that.
"Sometimes as a manager you have to hold your hands up and praise the opposition and today I thought Derby were magnificent. They were outstanding and thoroughly deserved the win."
Derby coach Andy Garner:
"We were totally in command as soon as the first whistle went.
"The first 20 minutes we were absolutely superb, dominated the game and were in their half constantly.
"We didn't get the goal our play justified but we stuck at it and when it came, it was a brilliant goal, a training ground goal really. Great hold up play from Conor Sammon and a typical Craig Bryson run and a good finish."