Former world titleholders David Lemieux and Sadam Ali will highlight the undercard of the Canelo Alvarez-Rocky Fielding undercard, Golden Boy Promotions announced Thursday.

Former middleweight titlist Lemieux will face Tureano Johnson in the 12-round co-feature on the card on Dec. 15 (DAZN) at Madison Square Garden in New York. Ali will face Mauricio Herrera in a 10-round fight.

"I'm extremely ready and looking forward to my next fight against Johnson," Lemieux said. "I didn't take a break since my last fight because I thought that I would be facing Canelo. Training camp has been great. Johnson is a solid opponent. I'm ready for an explosive performance and a great victory to end the year in a great way."

Lemieux (40-4, 34 KOs), 29, of Montreal, crushed Gary "Spike" O'Sullivan in a first-round knockout win on the Alvarez-Gennady Golovkin II undercard Sept. 15 to remain a probable future opponent for Alvarez.

"David Lemieux still has his eyes set on Canelo, and that night they will be in the same arena," Golden Boy Promotions CEO Oscar De La Hoya said. "Lemieux knows that if he loses against Tureano Johnson he can forget about any shot with Canelo."

Johnson (20-2, 14 KOs), 34, a 2008 Olympian from the Bahamas, has seen his career marred by injuries. His career was on the ascent in 2015 when he routed Eamonn O'Kane in a title eliminator to become a Golovkin mandatory challenger, but he tore his right rotator cuff in the decision win, had surgery and has only fought twice since, including 12th-round knockout loss to Sergiy Derevyanchenko in a title eliminator in his last fight in August 2017 in which he re-injured his shoulder.

"David Lemieux is a former world champion, so he's the kind of guy I'll have to defeat if I want a shot at the title," Johnson said. "I've had some setbacks in my career, but I'm feeling better than I ever have before. I'm excited to be part of this platform and will take advantage of this opportunity with a victory against Lemieux this December."

Former junior middleweight titlist Ali (26-2, 14 KOs), 30, of Brooklyn, New York, won a belt in a major upset when he outpointed Miguel Cotto in Cotto's final fight last December. But Ali lost the 154-pound title in his first defense when he was ruthlessly destroyed in four rounds by Jaime Munguia on May 12.

Ali will return to the welterweight division to face former junior welterweight title challenger Herrera (24-7, 7 KOs), 38, of Riverside, Calif. in a 10-round battle. Herrera has won two fights in a row.

Golden Boy also announced three other fighters who will appear on the card in 10-round fights, though they do not yet have opponents: lightweight Ryan "Kingry" Garcia (16-0, 13 KOs), 20, of Victorville, California, the 2017 ESPN.com prospect of the year, junior welterweight Yves Ulysse Jr. (16-1, 9 KOs), 30, of Montreal; junior welterweight Vergil Ortiz Jr. (11-0, 11 KOs), 20, of Dallas. The Garcia and Ortiz bout will be part of a "freeview" stream of preliminary bouts.

Also, junior lightweight up-and-comer Lamont Roach Jr. (17-0-1, 7 KOs), 23, of Washington D.C., will defend his regional belt against Alberto Mercado (15-1-1, 3 KOs), 30, of Puerto Rico, in a 10-rounder and Bilal Akkawy (18-0-1, 14 KOs), 25, of Australia, will face Victor Fonseca (17-8-1, 14 KOs), 25, of Mexico, in a 10-round super middleweight match.

Alvarez's main event is the first fight of the record-breaking five-year, 11-fight, $365 million deal he recently signed with sports streaming service DAZN, which also made a deal with Golden Boy to provide boxing content.

Another world title bout will also be on the card featuring junior lightweight titlist Tevin Farmer (27-4-1, 6 KOs), 28, of Philadelphia, in his second defense against Francisco Fonseca (22-1-1, 16 KOs), 24, of Costa Rica, but it has not yet been finalized.