ATLANTA, GA - JULY 29: John Isner returns a forehand to Gilles Muller of Luxembourg during the BB&T Atlanta Open at Atlantic Station on July 29, 2017 in Atlanta, Georgia. (Photo by Kevin C. Cox/Getty Images)
ATLANTA, GA - JULY 29: John Isner returns a forehand to Gilles Muller of Luxembourg during the BB&T Atlanta Open at Atlantic Station on July 29, 2017 in Atlanta, Georgia. (Photo by Kevin C. Cox/Getty Images)