A sport ball may include a casing that forms an exterior surface of the sport ball. The casing may incorporate a plurality of joined panels, including a closure panel. In addition, the ball may include a backing layer located radially inward of the closure panel, the backing layer extending beyond a peripheral boundary of the closure panel and at least partially overlapping with one or more panels adjacent to the closure panel. The backing layer may also include an opening located radially inward of the closure panel, the opening being smaller than the surface area of the closure panel. Also, the ball may include a bladder located radially inward of the backing layer, the bladder including a valve for introducing fluid into the ball, the valve extending through the opening and through the closure panel.