The Toreros (5-2) led 21-14 early in the second quarter when Lawrence led consecutive touchdown drives before the break.
Armstrong finished with 71 yards and Blake Martin led San Diego on the ground with 88 yards and a score. Ross Dwelley had five catches for 75 yards and a touchdown. Justin Priest added five catches for 71 yards and a TD.
Jeffrey Suarez Jr. had four receptions for 157 of Warner's 195 yards through the air. He scored both of the Royals' touchdowns including a 76-yarder in the first quarter.