HOUSTON, April 17 - World number nine James Blake moved into the U.S. Clay Court Championships quarter-finals by defeating 15-year-old Ryan Harrison in straight sets on Thursday.

Harrison, a qualifier, had beaten Uruguay's Pablo Cuevas in the first round to become one of only three players under the age of 16, to win an ATP match.

But the Texan resident was no match for top seed Blake who ran out a 6-3 6-2 winner and will face Argentine Agustin Calleri in the last eight.

"He has a good future -- the kid has got a very live arm and a very big serve for a 15-year-old which is only going to get bigger as he fills out more," Blake told reporters.
 
Calleri, the number five seed, defeated Chilean Paul Capdeville 6-2 6-1 to book his quarter-final spot.
 
American Wayne Odesnik reached his first career ATP quarter-final with a 6-3 7-5 win over sixth-seeded Israeli Dudi Sela.
Odesnik will be up against Argentine Sergio Roitman, who advanced with a 6-3 7-6 win over Russian Igor Kunitsyn.
 
Spain's Marcel Granollers-Pujol defeated Australia's Peter Luczak 6-3 6-2 and will next face Brazilian Marcos Daniel.

U.S. Clay Court Championships men's singles second-round results from Houston on Thursday:

1-James Blake (U.S.) beat Ryan Harrison (U.S.) 6-3 6-2
5-Agustin Calleri (Argentina) beat Paul Capdeville (Chile) 6-2 6-1
Sergio Roitman (Argentina) beat Igor Kunitsyn (Russia) 6-3 7-6(3)
Marcos Daniel (Brazil) beat Nicolas Massu (Chile) 7-6(3) 6-2
7-Marcel Granollers (Spain) beat Peter Luczak (Australia) 6-3 6-2
Wayne Odesnik (U.S.) beat 6-Dudi Sela (Israel) 6-3 7-5