The Brazilian was 15-0 at the time after going undefeated through his run in both Pride FC and the WEC, including his second-round submission over future UFC contender Chael Sonnen.
That's when Filho's entire life and career fell apart.
Sonnen was granted a rematch for Filho's WEC title due to the controversial nature of the ending surrounding their first fight, when the "American Gangster" got trapped in an armbar and screamed but claimed he never tapped out from the move. On weigh-in day, Filho came in at 189 pounds, four over the limit for a middleweight title fight.
The bout was then changed to a three-round nontitle match, and Filho's performance could only be described as abysmal. Sonnen won that night, and then as the WEC's middleweight division was absorbed into the UFC, Filho was left out of the deal and had no home to call his own.
The next few years for Filho were something akin to reading the gossip columns any time Lindsay Lohan's name is mentioned. A struggle with drug addiction and money issues had Filho actually retire in 2011, but that was short-lived and he returned to action a year later in his home country of Brazil.
Now for the first time since the loss to Sonnen back in 2008, Filho will step foot on American soil to fight for World Series of Fighting. The 34-year-old takes on David Branch at the promotion's second show Saturday in Atlantic City, New Jersey.
"His manager says Paulo's in a different place, obviously we all go through ups and downs in life and he's gone through his downs and now he's looking to make a return," World Series of Fighting president Ray Sefo told Bleacher Report about Filho's return. "He just fought in September I believe against Shogun's (Rua) brother Ninja (Murilo Rua) and stopped him, so I think right now he's in that point in his life before he retires from the game he wants to make another run at it and show the world what he's really made of."
The personal turmoil in Filho's life obviously bled over into his professional life and caused a once-great middleweight to falter and spiral down the ladder. Since losing to Sonnen in the WEC, Filho has posted a 7-3-2 record, which by all accounts isn't a bad mark at all, but it's a far cry from when he was undefeated and considered the No. 2 middleweight in the world.
Sefo has seen every part of the fight game, and he believes everybody is worthy of a second chance. This is Filho's time to prove he can still go with the best in the world.
"I think everybody deserves a second chance. Paulo Filho's one of those guys as well. Listen, you never lose your talent, you don’t lose your skills, but you've got to have the hunger and the drive to make a comeback," Sefo stated.
"It sounds like he does have that hunger and he does have that drive, and he definitely has all the skills. It's just a matter of time to give him that opportunity."
Filho will get that opportunity on Saturday night when he faces off with David Branch at World Series of Fighting 2. While it's unlikely Filho will ever regain the status he once carried as an elite middleweight in the world, he can still find some level of redemption by looking like there are still shades of that once-great 185-pound fighter lurking inside of him.
Damon Martin is a Featured Columnist for Bleacher Report. All quotes were obtained firsthand unless otherwise noted.