Without the injured Jo-Wilfried Tsonga, Lucas Pouille will face Andreas Seppi to open France's visit to Italy in the Davis Cup quarterfinals.
The 11th-ranked Pouille has a 4-3 record in the Davis Cup and won the decisive match over Belgium's Steve Darcis in last season's final.
It will be the first meeting between Pouille and Seppi.
Italy captain Corrado Barazzutti selected the 62nd-ranked Seppi over Paolo Lorenzi — who is ranked five spots higher — for the second singles spot.
Fabio Fognini will face Jeremy Chardy in the second match of the best-of-five series on outdoor red clay.
In Saturday's doubles, Simone Bolelli and Lorenzi will face Pierre-Hugues Herbert and Nicolas Mahut. Reverse singles are scheduled for Sunday.
Tsonga is out following minor knee surgery.
Isner rose to ninth in the rankings with his victory at the Miami Open last weekend. He'll play the 319th-ranked player at Belmont University, according to Thursday's draw . The 14th-ranked Sam Querrey follows with a match against Ruben Bemelmans.
Ryan Harrison and Jack Sock play Sander Gille and Joran Vliegen in doubles on Saturday.
Reverse singles follow on Sunday, with Isner against Bemelmans and Querrey facing De Loore.
The winner meets Croatia or Kazakhstan in the semifinals Sept. 14-16. The U.S. hasn't reached the Davis Cup's final four since 2012, but is 4-0 against Belgium in the Davis Cup.