Houston Dynamo midfielder Ricardo Clark (13) wins a header from D.C. United midfielder Perry Kitchen (23) during the first half of an MLS soccer match Saturday, March 2, 2013, in Houston. (AP Photo/Houston Chronicle, Smiley N. Pool)

Photo by: Smiley N. Pool

Houston Dynamo midfielder Ricardo Clark (13) wins a header from D.C. United midfielder Perry Kitchen (23) during the first half of an MLS soccer match Saturday, March 2, 2013, in Houston. (AP Photo/Houston Chronicle, Smiley N. Pool)