Chesterfield found the net in the sixth minute when Marc Richards volleyed in Ritchie Humphreys' cross but the striker had strayed offside and Wimbledon goalkeeper Ross Worner turned away a Jimmy Ryan shot three minutes later.
Tommy Lee had to be just as alert in the 18th minute to push away a Michael Smith drive from the edge of the area and the keeper made a superb double save in the 28th minute to deny Smith again.
But Chesterfield went ahead two minutes later when Jay O'Shea crossed from the right and Roberts arrived at the back post to sidefoot in from eight yards and Hird bagged a second in the 53rd minute when he headed in a Roberts cross.
Gary McSheffrey made his Chesterfield debut as a 77th minute substitute but George Francomb and Smith wasted late chances for Wimbledon before the leaders celebrated a fourth straight win.
- Sports & Recreation