Two goals in three minutes from Derby's Tom Lawrence was enough for the Rams to claim all three points from the opening round fixture and give new manager Phillip Cocu the perfect start to his time at the club.
Australian Midfielder Mooy was kept busy in midfield throughout the match and offered Huddersfield hope with a pair of long range efforts which tested Derby shot stopper Kelle Roos but he failed to hit the target.
However, that would prove to be the extent of the Socceroo's highlights as he struggled to make the most of his match leading 91 possessions and was guilty of giving the ball away too much.
Mooy was also seemingly overlooked to take the penalty scored by teammate Karlan Grant in the 30th minute despite being Huddersfield's designated penalty taker for the past two seasons.
Next on the schedule for Mooy is a potential match-up against Socceroos teammate Massimo Luongo when Huddersfield head to Loftus Road to take on QPR this Sunday.
