Max Bird scored his first goals of the season as Derby thrashed Northampton at Pride Park.
The midfielder netted twice before half-time to put Derby on course for their biggest win of the season.
Derby had twice gone close before Bird put them ahead in the 14th minute, steering in Conor Washington's low cross from the left.
Northampton were struggling to contain Derby but they should have done better when Washington ran between two defenders before beating Lee Burge with a low shot in the 22nd minute.
The game was over 10 minutes later when Conor Hourihane's pass picked out Bird, who slid a low shot past Burge from 10 yards.
Northampton made three changes for the second half but conceded again in the 49th minute when Tom Barkhuizen crossed for Nathaniel Mendez-Laing to score from 12 yards.
Barkhuizen and James Collins should have added further goals on a miserable night for Northampton, who did not manage a meaningful effort on goal in the 90 minutes.
Match report supplied by PA Media.