The ATP Tour shifts to clay this week with ATP 250 events in Houston and Marrakech

Casper Ruud, Reilly Opelka and Taylor Fritz headline the field at the Fayez Sarofim & Co. U.S. Men's Clay Court Championship in Houston, where the draw also includes former champions Cristian Garin, John Isner, Jack Sock and Steve Johnson.

Felix Auger-Aliassime is the top seed at the Grand Prix Hassan II in Marrakech as he pursues his second title of the year in a field rife with clay-court expertise. Albert Ramos-Vinolas and 2016 champion Federico Delbonis will also be competing in Morocco, where second seed Daniel Evans faces a first-round clash against three-time Marrakech champion Pablo Andujar.