British number two Cameron Norrie defeated American Zachary Slunts in straight sets to get to the second round of Delray Beach Open.
Norrie, winner of 2022, needed 90 minutes to seal the victory 7-5 6-4 for the world number 169.
Players traded in the serving breaks in a tight first set, which was played in Florida in hot and humid conditions.
A strong forehand down the line gave Norria a major second break, while the 29-year-old held comfortably to make the set.
With equally tight second set level to 4-4, Norria could not transfer five points of break in the eighth mammoth before she finally took over the sixth.
He then took the second of the two wrestling points on his service to organize the second round with the French second Semen Arthur Rinderknech or Gabriel Diallo, Canada.
