Marcelo says lifting the Copa Libertadores with Fluminense means more than his Champions League wins with Real Madrid.
The veteran left-back started his career at Fluminense before signing for Los Blancos in 2007 and returned to his first professional club earlier this year after a short spell at Olympiacos.
Now 35 years old, Marcelo won a club record 25 trophies at Real Madrid, including five Champions League titles.
And after helping Fluminense to their first ever Copa Libertadores on Saturday, as the Rio de Janeiro outfit edged out Boca Juniors after extra time at the Maracana, he admitted that this one was extra special.
"Real Madrid will understand," he told ESPN. "It's my most important trophy, at club level, because it's the club that raised me.
"Real knows they are always in my heart. It's hard to say. It's a double joy."
And he added: "I'm winning a very important title with my favourite club, the club that gave me all the tools to have my career, with the employees who saw me grow up.
"There's nothing more rewarding than that. It's priceless."
Marcelo is now one of a select group of players who have won both the Copa Libertadores and the Champions League, which also includes Ronaldinho, Neymar, Julian Alvarez and Carlos Tevez.
More Brazilian football stories
Chelsea have been tipped to sign a Brazilian wonderkid compared to the legendary Pele.
Meanwhile, Neymar is now Brazil's all-time top scorer, but insists he is not a better player than O Rei.
The former Barcelona and PSG forward, who now plays in Saudi Arabia, has been defended by his international coach after recent criticism. Fernando Diniz called Neymar "one of the greatest players in the history of football" last month.
