Derbyshire finished with aplomb nine minutes after coming on, and he was assisted by fellow sub Carlos Villanueva, who played a delightful chipped pass for Roque Santa Cruz to nod down to the England Under-21 striker.
Chile playmaker Villanueva made the difference in the match, an inspired tactical move from Paul Ince that allowed Rovers to move away from the destructive style that could have seen them reduced to 10 men on more than one occasion. Jimmy Bullard was on the end of some particularly rough treatment, with a brutal Keith Andrews challenge and an Antipodean four-footed tackle by Brett Emerton and Ryan Nelsen arguably worthy of more than the yellow cards issued by Lee Probert.
And later in the match, a retaliatory sliding assault by Stephen Warnock on John Pantsil somehow did not even draw a booking, even with Warnock glaring over his horizontal victim afterwards. Warnock was also spared by a technicality when he slid in late on Andrew Johnson - the ball had already gone out of play before he launched into the tackle.
Probert was consistently lenient, however. Pantsil escaped serious punishment for the foul on Keith Treacy that initially provoked Rovers, while Johnson was not even warned for kicking the ball away after he was caught offside.
Misdemeanours aside, it was an entertaining match that deserved more than its solitary goal.
Johnson nearly opened his Fulham account with a fourth-minute strike that the sprightly Paul Robinson tipped over in style, while a cameo of skill from Andrews saw him fire just wide in response to the Whites' early chance. Jason Roberts, Morten Gamst Pedersen, Santa Cruz twice and Villanueva all had good occasions to score for the hosts, while Emerton sent a cross-shot off the post after a surging run from midfield.
Fulham used the ball more entertainingly, but the frustrating Bobby Zamora missed three very good headed opportunities with one particularly bad miss when found unmarked on the hour. Soon afterwards Johnson also should have scored when he ran clean through, but he shot low at Robinson who saved well.
As the game wore on, both sides became more stretched and the introduction of the creative Villanueva and natural finisher Derbyshire gave Ince a winning combination to stop a run of two consecutive defeats and - after conceding four goals in each of those two losses - a hard-earned clean sheet.
