Isner Out Of Houston, Defending Champion Johnson Leads Field

After watching him hobble in the Miami final, John Isner did withdraw from Houston earlier in the week due to his foot. He was slated to be the top seed at the event, but his friend and countryman Steve Johnson will assume the top spot in America’s only ATP-level clay tournament.

Johnson has won Houston the last two years taking his last nine matches in Texas. In an American-heavy draw, he’s joined by seeds Jeremy Chardy, Cameron Norrie and Reilly Opelka.

Sam Querrey, Ryan Harrison, Tennys Sandgren, Mackenzie McDonald, Denis Kudla and Taylor Fritz are also in the field.

Forty-year-old Ivo Karlovic returns to the city he won at back in 2007. The big man opens against Harrison.