Emiliano Sala was "a golden boy, who gave everything for the team," according to his former Niort team-mate Paul Delecroix.
Sala is missing after the private plane he was on board disappeared near the Channel Islands on Monday.
Guernsey Police have resumed a search and rescue operation for the 28-year-old, who was confirmed as Cardiff City's record signing after leaving Ligue 1 Nantes over the weekend, although they believe his chances of survival are "unfortunately slim".
Argentinian striker Sala had spent his entire senior career in France, initially with Bordeaux. Before joining Nantes in 2015, he took in loan spells with Orleans, Niort and Caen.
Delecroix, now a goalkeeper for Metz who dumped Thierry Henry's Monaco out of the Coupe de France on Tuesday, played alongside Sala as he amassed an impressive goal haul for Niort in Ligue 2 during 2013-14.
"He scored 18 goals. I would remember that. Eighteen goals in 37 games," Delecroix told reporters at Stade Louis II.
"We couldn't have done much better really, as he's one of the most prolific goalscorers for Niort in one season.
"A golden boy who gave everything for the team. A guy you want to love. It's sad, I am sad."
Nantes' Coupe de France fixture against Entente SSG, which was set to be played on Wednesday, has been postponed, while fans of the club gathered in support of Sala at a vigil on Tuesday.
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