David Wagner shuffled his pack - and came up with a deserved winning hand.

It wasn’t so much the four changes the head coach made to his starting XI, although this was a big improvement on the below-par performance against

Preston North End.

More the fact that three substitutions, and Town’s impressive fitness levels and determination to push right to the end, finally unlocked one of the

Championship’s meanest defences.

While Steve McClaren contemplated his first defeat since starting his second spell as Derby boss, Wagner couldn’t stop himself racing onto the John Smith’s pitch to join in the celebrations after Elias Kachunga’s fine goal three minutes into the four which were added on by Merseyside referee Peter Bankes.

VIDEO - See Town's celebrations of the victory:

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The German was made to watch what remained of an entertaining match from the stand after being sent from the dug-out and will wait to discover if there are any further repercussions.

But that couldn’t spoil his delight as his side got back to winning ways after those losses at home to Sheffield Wednesday and away to Preston.

Town are back up to third in the table after their ninth win in 14 matches and sixth in seven on their own turf .

Kachunga’s fifth goal of the season took them to 28 points.

In the four other seasons since being promoted from League One, Town have only once got the that number before Boxing Day (in 2012/13, when they reached 28 on November 24 and were 10th in standings).

That alone reflected the progress made under Wagner, but it’s obvious in so many other ways.

Victory in pictures:

Derby, for instance, had been beaten only once before by Town in eight clashes since that 2012 return to the second tier.

And while there might have been upheaval at the East Midlands club this season, Nigel Pearson’s successor McClaren can call on some expensive and talented footballers..

Before their trip to West Yorkshire, they had conceded just 10 goals in 13 games (only Brighton and Hove Albion could better that figure), and it looked as though this match was going to end goalless.

Town, with Michael Hefele, Dean Whitehead, Kasey Palmer and Nahki Wells in for Mark Hudson, Aaron Mooy, Jack Payne and Sean Scannell, had fashioned the better chances.

But Scott Carson made particularly good saves from Wells and Bunn, who replaced Rajiv van La Parra after 61 minutes, when Wagner also brought on Mooy for Whitehead.

The robust Whitehead and Jonathan Hogg had combined well to help limit Derby’s attacking, but Mooy, who had looked jaded at Preston, added a touch of creativity, while it was from Bunn’s inviting cross that Kachunga headed home.

When the substitute’s board went up after 74 minutes to signal Jack Payne’s entrance, some might have thought Kachunga,who has played so many minutes since his signing on a season-long loan from Ingolstadt, or Kasey Palmer might have been sacrificed.

But Wells made way, thus allowing Chelsea loanee Palmer to complete a first full Town match and giving Kachunga chance to seal victory.