The Eagles lead by two goals before Nemanja Matic sealed a dramatic come-from-behind 3-2 win with a stoppage-time stunner.
Palace copped a late winner from Tottenham last weekend, and Townsend, who scored againstUnited, said the players were "devastated" after Monday night's loss.
"Twice in eight days we have thoroughly deserved at least a point, if not all three," he told the club website.
"We've been undone by a bit of quality right at the end. Everyone is devastated in that dressing room."