Frank Lampard goes up against former Derby manager Gary Rowett in the Sky Bet Championship on Wednesday night, as the Rams face Stoke live on Sky Sports Football.
But have Derby improved under their new boss? Here, we take a look at some of the changes he has made...
Faith in youth
While Rowett's Derby team was built on a platform of experience, Lampard has made huge changes to the age of his playing squad and starting line-up.
The likes of Curtis Davies, Ikechi Anya, Cameron Jerome and Bradley Johnson all started their play-off semi-final defeat to Fulham at the end of last season, but have since been shepherded away from the starting line-up.
The average age of Rowett's starting XI last season was 29 years and 199 days, and that has come down by more than three years this season to an average of 26 years and 259 days.
Fikayo Tomori (20), Mason Mount (19), Harry Wilson (21) and Jack Marriott (24) have all made a big impression largely in place of those four players above.
Focus on possession
While Derby are not necessarily creating more chances per game than they were last season, they are dominating games more.
Rowett's side averaged 47.8 per cent possession last season, while under Lampard it has been 57 per cent so far, an increase of almost 10 per cent.
Lampard's side are also playing more than 60 passes more per game on average (466 to 404), and their passing accuracy is also up (77.9 per cent compared to 73.9 per cent under Rowett).
It appears as though Lampard's side have a far clearer identity in terms of the way they want to play.
There are some stats that haven't changed too much. After 18 games of last season, Derby had actually earned one point more (32 to 31), scored more goals (29 to 27) and conceded fewer (20 to 21).
Lampard's side are having more shots per game (14.2 to 12), but fewer of those attempts are turning out to be clearer chances. Derby had an Expected Goals (xG) rate of 1.43 last season, compared to 1.09 this campaign.
That is probably largely due to the fact that far more of Derby's shots this season are coming from outside the box (7.2 per game this season to 5.9 last), with the likes of Wilson and Tom Lawrence regularly trying their luck from long range.
Biggest test to come
Arguably the biggest change that Lampard has to make it still to come. Derby have often found themselves in great positions in recent years to push for promotion, but a mixture of late collapses and play-off heartache have too often seen them fall out of contention at the final hurdle.
Rowett's Derby were 45 minutes away from the play-off final at Wembley in May but conceded two second-half goals against Fulham at Craven Cottage to see their dreams dashed for another year.
Rowett then moved on to Stoke as he thought his chances of promotion were better in the Potteries, but it has not clearly worked out for him as of yet and he will be ready for a frosty reception from the away fans on Wednesday night.
Victory on Wednesday night would delight the travelling fans and surely show that Lampard is capable of taking Derby further than Rowett managed at the helm.