One of the possible opponents of Manny Pacquiao for his swan song next year is the unbeaten Terence Crawford, but the retired and undefeated Floyd Mayweather Jr. had a warning for the young slugger in case he faces the former eight-division champion. 

In a report by Fighthype.com, Mayweather stated, "If Terence Crawford happens to fight Manny Pacquiao, I want to let him know that it's not going to be easy. Even though I know I made it look easy, it's not going to be easy."

"He's a lot better than what I thought he was. From me being in the ring with Manny Pacquiao, I take my hat off to him and I can see why he went so far in his career," the number one pound-for-pound also said. 

In the report, Mayweather also stated that Pacquiao hits harder than Yuriorkis Gamboa, who Crawford defeated last year via knockout. 

Mayweather then expressed his admiration for Crawford but he does not want the 28-year-old boxer to be complacent if ever he had the chance to face Pacquiao. 

"I really, really like that kid. I don't want to take anything away from him because he can really fight. He can fight, but I don't want him to think that just because I made it look that easy with Pacquiao, it's going to be that easy," the 38-year-old Mayweather explained. 

Crawford, along with the likes of contenders Amir Khan and Kell Brook, are on top of the list as possible final career-opponents for the Filipino boxing icon who plans to retire after next year's bout. 

Khan is leading the race, but recent reports said that just like with Mayweather, he is again playing the waiting game as Pacquiao has yet to sign the contract to officially make the fight happen. 

The 28-year-old British slugger's camp and Pacquiao's promoter, Top Rank's Bob Arum, reportedly are in talks for a possible fight since earlier this year.