Carlos Eduardo only scored six goals in 40 appearances for FC Porto and their B team last season
Carlos Eduardo scored five goals as Nice thrashed Ligue 1's bottom club Guingamp.
The 25-year-old, who is on loan from FC Porto, had only scored one goal in his opening five games for the French club.
But he netted a first-half hat-trick after Claudio Beauvue had given the hosts the lead, with Alassane Plea making it 4-1 at half-time.
Eduardo added two more with Ronnie Schwartz scoring for Guingamp and Eric Bautheac completing the rout.
The Brazilian fell two short of the individual record for a Ligue 1 game, achieved by Sochaux's Andre Abegglen and Rouen's Jean Nicolas in the 1930s - both in games against Valenciennes.
Elsewhere in France, league leaders Marseille's eight-match winning run is over as they lost 1-0 to Lyon.
Yoann Gourcuff's goal took Lyon up to third, one point behind second-placed Paris St-Germain and five off Marseille.
