The Dynamo (7-8-6) tied it on a set-piece after a foul conceded by Sporting's Amadou Dia on the right wing. Brad Davis' service found Clark at the 6-yard box and his header got behind Tim Melia in the top left corner.
Kansas City (9-4-6) scored early. Sporting was awarded a free kick in the sixth minute after a foul by Raul Rodriquez. Benny Feilhaber sent the kick into the middle of the penalty area and Dominic Dwyer rose for a header that beat Tyler Deric to the bottom left corner.
Houston almost tied it in the 32nd minute, but Melia made a sprawling save on Tim Davis' left-footed rocket from the top of the box.