Guerrero's WBC World Interim Welterweight strap was on the line as the 29-year-old Mexican-born California southpaw looked to cement his full WBC credentials against Miami-based Haitian-American Andre Berto, also 29.
The two men stepped into the Citizens Business Bank Arena ring for an important clash. Guerrero walked away with a UD victory, giving Berto a second loss on his record and keeping his own defeat tally to one (until he met Floyd Mayweather Jr the next year).
Nicknamed "The Ghost", the Mexican southpaw had previously held IBF honours at feather and super-featherweight before winning the interim WBA and WBO World Lightweight crowns.
His next move was a vast one, stepping up to the 147lb division after 15 months away from the ring and defeating Selcuk Aydin with a hardworking 12-round decision.
And then he beat Berto, a natural welterweight and former WBC World champ, in what was one of the biggest challenges of his career.
For two-time welterweight world champion Andre Berto, a shot at the interim strap presented him with a chance to build his way back to full honours.
The Haitian-American was a dominant force in the welterweight division, winning the WBC crown in 2008 and defending it on several occasions.
However, in April 2011, Berto surrendered his WBC strap to Victor Ortiz in a fiery encounter where both fighters were dropped to the canvas and eventual winner Ortiz was docked a point in the 10th. The challenger still took a unanimous decision, and left Berto with a first career defeat.
On the road to recovery, the 29-year-old had since beaten Jan Zaveck to secure the IBF Welterweight title. He had hoped to add the interim WBC to his honour roll but Guerrero ensured this wasn't to be.