Brad Spencer netted a second with seven minutes left before being shown a straight red card five minutes later as Forfar finished with ten men.
Raith Rovers went down 2-1 at Brechin City.
Substitute Kevin Nisbet took just 60 seconds to make his mark, netting his 21st goal of the season with a right-footed shot.
But Brechin were level seven minutes into the second half when Euan Smith took Jordan Sinclair’s pass to score with his right boot. Ross Kavanagh won it midway through the second half.
East Fife closed in on the top two when they came back from 2-0 and 3-1 down to win 4-3 at Stranraer. Grant Anderson gave Stranraer a 21st-minute lead before Innes Cameron made it 2-0.
Kevin Smith pulled a goal back w four minutes after the break but Joao Victoria extended Stranraer’s lead with a debut goal.
East Fife roared back with two goals in two minutes. Craig Watson netted after 70 minutes and then Anton Dowds equalised. Dowds then put East Fife in front with his second goal.
Elsewhere, Dumbarton and Montrose drew 1-1. Boris Melingui had better luck of late as his strike put Dumbarton in front but Martin Rennie equalised from the penalty spot.
Stenhousemuir warmed up for their Scottish Cup replay against Aberdeen by dumping Airdrieonians 1-0 at Ochilview.
Thomas Halleran broke the deadlock 16 minutes from time when he scored direct from a free-kick.