Bernard Tomic retired from his Open de Nice Cote d'Azur first round match against qualifier Gianni Mina due to illness less than a week before the start of the French Open.
The fifth seed from Australia lost the first set 6-2 and decided he could not continue as he was suffering from a virus just days ahead of Roland Garros.
Frenchman Mina, ranked 269 in the world, broke in the first game of the match and then went a double break up before serving out the first set to love. Mina was then able to celebrate his first tour-level victory as Tomic's week was cut short.
Second seed John Isner is through to the third round as a result of his 7-6 (7-3) 4-6 6-3 victory over fellow American Steve Johnson.
The 30-year-old sent down 16 aces in a powerful display of serving and plans to reward himself with a leisurely day off on Wednesday.
"I took a boat out on the water at the weekend and I'm trying to enjoy myself. It's so beautiful here. I want to have some fun," he told the ATP World Tour website.
"I do have to practice and take care of what I do, but I also want to have fun while I do it."
Sixth seed Nick Kyrgios sealed his place in the second round courtesy of a 7-6 (7-5) 6-2 success against Mikhail Kukushkin of Ukraine, edging a first-set tie-break before claiming two breaks in the second set.
Juan Monaco, seeded eighth, took just 55 minutes to end Sam Querrey's hopes of reaching the third round as he eased to a 6-3 6-1 victory over the world number 38.
Lucas Pouille, James Duckworth, Alexandr Dolgopolov and Dusan Lajovic were all first-round winners on Tuesday.