Derby had beaten Wycombe 2-1 on Tuesday thanks to Andre Wisdom's stoppage-time winner but Rooney declared himself unimpressed straight after and made five changes for this one.

Nathan Byrne, Lee Buchanan, Max Bird, George Edmundson and Patrick Roberts came in, with the latter duo making their first Rams starts.

The Hornets, who made a single change following their 1-0 win at Preston on the same night, constantly looked to the speedy Ismaila Sarr down the right as soon as they were able to break down Derby's possession game.

And it was Sarr's pace that led to Pedro's 19th-minute opener, although fortune certainly favoured the hosts as the winger's cross was met by Andre Wisdom, who saw his attempted clearance hit the teenager's trailing leg and cross the line.

Derby had only themselves to blame however for dozing off from a corner two minutes later. Nathaniel Chalobah flicked the ball back to Hughes on the right of the box and the former Rams player saw his drive creep in at the far post with help from a deflection off Nathan Byrne.

Derby were instantly deflated, and relieved when balls across their box eluded first Chalobah and then Pedro.

The Rams were controversially denied a goal from a corner in the 40th minute. Goalkeeper Daniel Bachmann, who had unconvincingly punched one over his own bar seconds earlier, was adjudged to have been impeded by Wisdom as Colin Kazim-Richards came charging in to head home.

The half ended with Martyn Waghorn bursting through and lofting over both Bachmann and his crossbar.

Pedro was on the end of Hughes' fine floated ball into the box but the Brazilian's volley was straight at goalkeeper David Marshall.

Kazim-Richards blasted a Rams reply wide before Pedro went close again at the other end, hooking over his own shoulder and just over the bar.

Sarr passed up an opportunity to wrap up victory 20 minutes from time when he cut inside on the right but could not hit the target with a left-footed effort.

Derby gave themselves hope in the 77th minute when Hornets defender Troost-Ekong diverted Byrne's cross into his own net as substitute Lee Gregory moved in to pounce.

Byrne's corner almost caught Bachmann out at his near post but no Derby player could capitalise on the Austrian's push into a crowded six-yard box, and Watford successfully negotiated five nervy minutes of added time that saw Rams keeper Marshall go up for two corners.