Tournament officials said the event would be shortened to 54 holes and was slated to resume Monday morning.
Vegas made birdie putts from beyond 7 feet on the first two holes to reach 13 under, then parred three straight before a steady rain, accompanied by intermittent thunder, forced organizers to clear the water-logged TPC Louisiana after little more than two hours of play.
Stuard, who has not bogeyed a hole in the tournament, had one birdie Sunday. Like Vegas, he'll resume play on the sixth hole.
Top-ranked Jason Day was in a five-way tie for fifth at 10 under through 44 holes.
Rain, which also delayed play Thursday and Saturday, is again forecast Monday.
