A door assembly for a horizontal axis washing machine includes a door rotatably mounted to a front panel to permit selective access to an opening of the washing machine appliance. A sub-door is rotatably mounted to the door and is movable between an open position and a closed position. The sub-door defines a pretreat basin for collecting wash fluid from a wash fluid supply when the sub-door is in the open position for pretreating an article of clothing. After the pretreatment procedure is complete, the sub-door may be pivoted toward the closed position such that the article of clothing and the collected wash fluid are passed directly into the tub through a door opening and drain conduit.