McDonald and Moult propelled Motherwell into the top six with a 2-1 victory over Ross County in Dingwall.
It was a vital win and it delivers some breathing space ahead of the next three tough fixtures.
McDonald pounced on a Jay McEveley mistake to open the scoring in the 28th minute but the County defender redeemed himself by heading an equaliser six minutes later.
The unmarked Moult headed home from Steven Hammell's inswinging corner nine minutes after the interval and the visitors held on for a crucial win.
Moult had the ball in the County net in the 17th minute but he was flagged offside and the home defence were guilty of giving the ball away too easily as Lee Lucas picked up a loose ball, but his effort was blocked in front of goal.
County first threatened in a breakaway move but Craig Samson tipped the overlapping Marcus Fraser's ball over the bar.
Well took the lead three minutes later when McEveley failed to cut out a through ball from Lucas and McDonald drove into the box and and fired past Scott Fox
McDonald came close again a couple of minutes later when he cut inside and blasted a shot over
McEveley was soon celebrating when Martin Woods' corner found the defender on the edge of the six-yard box and he sent looping header over Samson's head and into the net as the Motherwell goalkeeper protested in vain, claiming he had been impeded.
County were lifted and Samson saved well from Woods' header.
County made a double substitution at the start of the second half with Milan Lalkovic and Jason Naismith replacing Christopher Routis and McEveley respectively
Woods drifted a left-foot just wide but it was Motherwell who restored their lead when Moult rose highest to nod the ball home from close range
A delicate chip into the box from Woods almost let Alex Schalk in on goal but Samson rushed off his line to make a timely intervention
County were going all out for a leveller and Schalk stung the hands of Samson when he cut inside and let fly and Boyce was unable to knock in the rebound
The chances kept coming and, after a Woods header was cleared behind, Michael Gardyne sliced a shot well wide of target
County continued to dominate until the final whistle but they just could not find that elusive equaliser.
Ross County 1 Motherwell 2
Attendance 2,511
Team: Samson, Tait, McManus, Heneghan, Hammell (Jules 78), Cadden, Lasley, McHugh, Lucas (Clay 70), McDonald, Moult (Ainsworth 92)
Source: DSG