The contest had to be abandoned last month when torrential rains made the field at RFK Stadium unplayable. Rains fell again Wednesday, forcing yet another delay of an hour.

The original stoppage of play last month came in the 19th minute and Mullan's goal was scored in the 20th on an assist from Geoff Cameron.

Brian Ching clinched it by scoring in the 79th minute, boosting Houston to 5-4-8 and moving the Dynamo to within a point of conference-leading Real Salt Lake. Houston had played to ties in its three previous contests.

United had a four-game winning streak snapped, falling to 7-8-1 and remaining deadlocked with Toronto for fourth place in the Eastern Conference.