The Rams created more opportunities throughout the match and the 25-year-old United States international claimed victory with a well-directed header in the 82nd minute.

It was just a third league home defeat of the season for Paul Heckingbottom’s play-off hopefuls but they remain in the top six.

John Eustace’s team started brightly with goalkeeper Jack Walton – in for the injured Daniel Iversen – making an excellent reaction save to tip Sondre Langas’ header over the crossbar inside four minutes after the Norway international met Joe Ward’s long throw.

Lewis Dobbin tried to get the hosts moving with a solo run down the centre of the pitch but his final 25-yard strike was always curling away from the goal.

Ward was a late addition to the team with Danny Batth injured in the warm up and his long throws were working a treat, again finding Langas in the box and, again, the defender made Walton work with a header on goal in the 23rd minute.

That chance was either side of two high, wide and not-so handsome Preston efforts from Ali McCann and Milutin Osmajic, both from in and around the edge of the box when the target was there to be hit.

Without a shadow of a doubt, the best chance of the match in that moment fell to Agyemang, minutes into the second half and inexplicably, the American blazed over from six yards as Ben Brereton Diaz’s daisy-cutting cross landed perfectly in his path.

Just moments later, Walton just about stayed tall enough to deny Rhian Brewster, who surged through on goal before trying to dink the North End stopper and Odel Offiah nearly spooned his clearance into his own net.

How Preston survived that early second-half onslaught is anybody’s guess, with a speculative long-range effort from substitute Alfie Devine the best they could muster in response on the hour mark.

Ten minutes later, it was Devine who was looking for divine intervention once more, surging down the field and dragging a shot narrowly wide from just outside the box.

The winner came from Brereton Diaz, who initially forced Walton into a smart stop with a teasing half-volley before picking out Agyemang with a delicate cross.

The striker planted his header into the ground and away from the Preston goalkeeper’s despairing dive, marking his seventh goal of the campaign.

It took until the 88th minute for the hosts to record a shot on target and even then it was a tame one, with Devine’s delicate 25-yard attempt falling straight into the arms of Jacob Widell Zetterstrom as Derby took maximum points home.