
In a low-key encounter, largely down to the sweltering hot conditions at the Proctor Cars Stadium, Slew's strike before the break separated the two sides on an afternoon of few chances.
The summer signing for Matlock capitalised on a cruel deflection with 14 minutes gone and Lee Bullock and Nathan Haslam's men were unable to muster a response, with Marcus Giles and Priestley Griffiths both going close for the Seasiders as they suffered an opening day defeat for the first time in five years.
Jake Day's cut back took a nick off the foot of Daniel Rowe which set the ball up nicely for Slew to poke the ball home from close range.
The game as a whole brought little action of note, perhaps in part because of the red-hot conditions in Derbyshire. Neither the Blues nor their opponents were able to carve out many meaningful opportunities, despite the efforts of both sets of players.
Slew fired a warning shot early on as he headed wide before Al Byrne called Shane Bland into action with a routine save. The Gladiators were tested only occasionally at the other end. Giles prodded the ball off target before Lewis Hawkins struck over the crossbar from range with 39 minutes played.
Matlock thought they had a second on the stroke of half-time, only to be denied by the referee who had penalised them for a foul on Rowe inside the area.
The hosts went close to adding another goal just after the restart - Slew once again the man involved but he curled wide of the post after cutting inside.
The Whitby bosses waited until the final half hour before shuffling their pack. Jonathan Franks came on for Giles who was having a frustrating afternoon in front of goal.
A disappointing afternoon for the Seasiders looked to be petering out, but half-chances came their way late on.
The best opportunity fell the way of Griffiths following a corner. The ball fell to him on the edge of the area, but his powerful strike was bravely blocked and cleared.