WBC world welterweight champion Danny Garcia and WBC and WBO super-lightweight king Terence Crawford appear to be on a collision course.
Garcia (32-0-KO18) is on the hunt for a big name having stepped up a division to claim the vacant title against Roberto Guerrero in January, while Crawford (29-0-KO20) unified titles by easily outpointing Viktor Postol in July.
Nevada's Crawford, 28, said to 'Swift' on social media: "Yo [sic] dad said I'm a made up champion for beating the guy y'all was scared to fight.
"So I tell you what. Tell your dad to make the fight and I'll show him how much of a paper champ I am at your weight and for your belt."
Garcia responded: "You're doing what I did 3 years ago. I ain't no little (Yuriorkis) Gamboa or stiff Postol. I end careers - check my track record. Your fight did 50k buys. Lol [sic]. If you wanna do real numbers and get defeated, tell [promoter] Bob Arum to call Al [Haymon]."
Crawford then appeared to accept the challenge, adding: "That same stiff guy y'all paid so you didn't have to fight? Look, I'm not them old guys you have been fighting. You know that. No problem."
Crawford first became a world champion at lightweight when he defeated Ricky Burns in March 2013, while Garcia boasts stoppage victories over the likes of Amir Khan, Erik Morales and Paulie Malignaggi.