Casas, who had been struggling with poor form of late, pieced together rounds of 68-72-140 to come in joint fourth in the two-day qualifying phase in the tough Lake Merced Golf and Country Club in Daly City.
"Good game and I made it to the playoff," said Casas in a text message to Boy Blue Ocampo, operations tour manager for Asia of img, Casas’ local agent.
Casas beat former RP Open champion Anthony Kang (68-72), Aaron Meeks (69-71) and Todd Fischer (72-68) in the playoff.
Only three berths were staked in the Lake Merced qualifier, one of 12 sectional qualifying tournaments, with a fourth one given reserve status.
Californian Andy Miller topped the elimination with 67-68-135 followed by amateur Ricky Barnes (70-67) and Paul Goydos (66-72-138).