Martyn Waghorn scored a hat-trick and Mason Mount netted on his comeback as Derby thrashed struggling Rotherham 6-1 at Pride Park.

On-loan Chelsea midfielder Mount marked his return after missing 10 games with a hamstring injury by winning the penalty that put Derby on course for only a second win in eight league matches and a return to the top six.

Waghorn scored either side of a Bradley Johnson header before Mount got the fourth and then set up Duane Holmes. Waghorn's second spot-kick gave Derby six goals in a game for the first time since 1996.

Rotherham were outplayed and Richard Wood's header was the only bright spot as they remain in the relegation zone.

The game promised goals from the start with both teams going close in the opening five minutes.

First Tom Lawrence forced the ball through to Waghorn but the striker delayed his shot and was crowded out.

Rotherham responded by opening Derby up in the fifth minute as Joe Newell got in on the left. His low cross just evaded Ryan Williams, who collided with a post and needed lengthy treatment.

Mount then won a penalty when he was tripped as he turned away from Ben Wiles and Waghorn sent Marek Rodak the wrong way with his 12th-minute spot-kick.

The goal lifted Derby and Lawrence fired into the side netting but Rotherham almost equalised in the 27th minute when Newell's corner found Semi Ajayi, whose first effort was blocked on the line by Holmes before his follow-up was saved by Kelle Roos.

Derby then took a large step towards victory with two goals in the space of four minutes.

Scott Malone crossed for Johnson to head in from eight yards in the 39th minute and then Holmes picked out Waghorn to glance the ball past Rodak in the 42nd.

Roos turned behind a Newell free-kick but Derby went in at half-time knowing they were in complete control and Rotherham's slim hopes were extinguished three minutes into the second period.

Jayden Bogle whipped the ball in from the right and Mount finished clinically from 12 yards.

Wood headed in a corner in the 53rd minute but Derby restored their four-goal cushion when Holmes volleyed in Mount's header 10 minutes later and Rotherham's afternoon got worse with 20 minutes to go.

Lawrence was tripped as he tried to go round Rodak and Waghorn again sent him the wrong way as Derby scored six at Pride Park for the first time.