A pair of Americans have won their second-round matches at the U.S. Clay Court tennis championships in Houston, Texas.

Second seed Andy Roddick upended fellow American Paul Goldstein 7-5, 6-4, while number three James Blake beat Hungary's Attila Savolt 6-2, 7-6.

Number five Vincent Spadea of the United States was not as lucky, falling to Brazil's Fernando Meligeni in three sets, 4-6, 7-6, 6-3.