An unbeaten but unknown, unproven opponent has replaced Jean Pascal on short notice.

BoxingScene.com has learned that Venezuela’s Dervin Colina will battle Badou Jack on the Floyd Mayweather-Logan Paul undercard Sunday night. Jack (23-3-3, 13 KOs) and Colina (15-0, 13 KOs) are scheduled to square off in a 10-round light heavyweight bout, Showtime Pay-Per-View’s co-feature before Mayweather meets Paul in an eight-round cruiserweight exhibition at Hard Rock Stadium in Miami Gardens, Florida.

The Swedish-born, Las Vegas-based Jack was supposed to challenge Quebec’s Pascal in a WBA world 175-pound championship rematch. Jack announced Friday night, however, that the 38-year-old Pascal tested positive for three banned substances and thus was removed from their 12-round fight.

According to Yahoo! Sports’ Kevin Iole, Quebec’s Pascal failed Voluntary Anti-Doping Association tests for three steroids – Drostanolone, Drostanolone Metabolite and Epitrenbolone.

Jack immediately condemned Pascal on social media and stated that he suspected Pascal was “dirty” before their first fight, which Pascal (35-6-1, 20 KOs, 1 NC) won by split decision in December 2019 at State Farm Arena in Atlanta. Pascal claimed soon thereafter on social media that he didn’t knowingly take any performance-enhancing drugs.

Jack, a former super middleweight and light heavyweight champion, and his team considered other opponents before settling on Colina.

The 33-year-old Colina has won six straight bouts by knockout and is ranked 13th among the WBA’s contenders in the super middleweight division. He also has competed at light heavyweight, but overall, he has faced a very low level of opposition.

Before his knockout streak started, Colina settled for an eight-round, split-decision victory over Colombia’s Dionisio Miranda, who entered their December 2018 bout with a record of 22-17-1. Colina’s biggest victory was a first-round technical knockout of another Venezuelan boxer, Argenis Espana, who took a 13-0 record, including 13 knockouts, into their fight in July 2019.

The 37-year-old Jack most recently beat another undefeated, untested opponent, Blake McKernan (13-1, 6 KOs), by unanimous decision in an eight-rounder November 28. That fight was part of Triller’s Mike Tyson-Roy Jones Jr. undercard at Staples Center in Los Angeles.

Showtime Pay-Per-View’s undercard Sunday night will include two bouts before Jack-Colina.

Former IBF/IBO/WBA 154-pound champ Jarrett Hurd (24-1, 16 KOs) is set to face Luis Arias (18-2-1, 9 KOs) in a 10-rounder. In a cruiserweight exhibition, retired NFL Pro Bowl wide receiver Chad Johnson is scheduled to battle Brian Maxwell, a mixed martial artist who lost his only professional boxing match.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.