Japan's Kei Nishikori said on Sunday that it was "sad" to see Argentinian Nicolas Kicker found guilty of match-fixing.
Nishikori, who saw off French youngster Maxime Janvier 7-6 (7/0), 6-4, 6-3 in the French Open first round, was due to practice with Kicker at Roland Garros last week.
World number 84 Kicker was found guilty of fixing two matches on the second-tier Challenger Tour in 2015 and could face a lifetime ban.
"Well, yeah, honestly, very sad. Because I think he's good player. He can be a top-50 player," said Nishikori after his win on Sunday.
Kicker reached the third round of the Australian Open in January this year and the also the third round at the Indian Wells Masters.
He was also found guilty of failing to report a corrupt approach and of not co-operating with a Tennis Integrity Unit investigation into the allegations made against him.
"Well, I don't want to say I understand him, but I think some of the players have a tough life from the beginning," added Nishikori.
"I think some people have no money, and you've got to be strong to say no to everything."
Nishikori had to work hard to get past 21-year-old wildcard Janvier, but was always the stronger player on Court One.
The 19th seed said he knew little about his 304th-ranked opponent before the match, so had to change his tactics during the contest.
"He was playing pretty good tennis. I didn't know him, so I checked a little bit, but I kind of had to check in the match.
"He was playing very aggressive. I think I've never seen how aggressive he plays."
Nishikori has risen back up the rankings after a strong clay-court season, which included a final loss to Rafael Nadal in Monte Carlo, having missed the early months of the campaign with a right wrist injury.
The world number 21, who reached the French Open quarter-finals in 2015 and 2017, will next take on either home hope Benoit Paire or Spaniard Roberto Carballes Baena.
Janvier started brightly, with Nishikori having to stave off five break points in the fifth game as the opening set went to a tie-break.
But the former world number four raced through the breaker without dropping a point as Janvier appeared to feel the pressure.
From then on Nishikori was in control, although he did have to save two break points to serve out the second set, before easing through the third.