Billy Clarke celebrated his return to the starting line-up with two goals as Reds made it five League One wins out of six against MK Dons.
On his first league start since September 1, Clarke profited from good work by strike partner Gary Alexander and then substitute Mark Connolly to score on 21 and 90 minutes.
Reds rode their luck at times, particularly during a spell in the first half when the visitors twice hit the bar and were denied on other occasions by stoic Crawley defending and some solid work by goalkeeper Paul Jones, who won the man of the match award.
As well as Clarke, Dannie Bulman was restored to the starting line-up but neither side looked particularly threatening in a cagey first 15 minutes. Clarke showed he meant business when he spun off Dean Lewington to create space for a shot which flew wide before he broke the deadlock.
The visitors failed to properly clear a corner by Nicky Adams and Alexander fired a low cross into the box from the left and Clarke reacted quickest to steer the ball into the bottom corner.
It provoked a spirited response from the visitors, who began to get on top in midfield and stretch the home defence. MacDonald broke clear of the offside trap but Jones was out quickly to save when the ex-Reds' striker delayed his shot then Jones got fully behind a drive from the increasingly influential Luke Chadwick.
Reds really rode their luck in a two-minute spell just before the break. Chadwick stood up a cross for another former Crawley player Danny Powell and his header crashed back off the underside of the bar before Angelo Balanta's cross was met by MacDonald but he failed to get enough weight on his shot from close range and it kissed the crossbar before Reds cleared.
Half-time came just at the right time for Reds who re-organised and looked a lot more solid in the second half. At times the visitors' passing was crisp and concise but direct efforts on the home goal were few and far between and on the break Reds always looked a threat.
Adams forced David Martin to palm away his stinging shot and Alexander's curling effort drifted just wide before Clarke got into an excellent position only to hit his shot over the bar.
It looked as if Reds would get the job done but just to make sure they scored a second goal on the stroke of full-time. Connolly, who had only just come on, created the chance with a pin-point pass to Clarke who swivelled and buried a low shot into the bottom corner before being mobbed by his delighted team-mates.
Three more points and a chance for Reds to strengthen their play-off bid on Saturday with another home game against Oldham Athletic.