Calzaghe and Froch are two of the best fighters Britain has ever produced. Their careers overlapped a bit, but they never actually fought each other. This has led to a lot of debate about who would've won if they had.
Kessler lost to Calzaghe in 2007, giving up his WBA and WBC titles. He then fought Froch twice, winning a close contest in 2010 during the Super Six tournament, but losing on points in a thrilling rematch in 2013.
When asked about the two fighters, Kessler told the Daily Mail:
"It is difficult to say who is best. Joe was not a puncher – he was fast but he was hitting with the inside of his glove but he got the points when they landed. He was mentally strong. He was in very good shape all the time. Carl is more of a fighter and throws lots of punches one after the other. He wants to trade punches. If Carl was in there throwing his big punches and his uppercuts, then he would have hurt Joe."
Despite praising both fighters, Kessler leaned towards Calzaghe when pushed for a prediction:
"Who would win out of those two? I would think Calzaghe. Maybe."
Calzaghe retired unbeaten after 46 fights, having competed at super-middleweight and light heavyweight. He scored notable wins over Bernard Hopkins and Roy Jones Jr. Froch, known as "The Cobra," made his name at super-middleweight. He's best remembered for his two fights against George Groves, winning the first with a controversial stoppage and the second with a knockout at Wembley Stadium in May 2014.
Both Calzaghe and Froch have since been recognized for their achievements. The BBC reports that they've both been inducted into boxing's Hall of Fame, cementing their places among the sport's all-time greats.