Eight-division world champion Manny Pacquiao should be wary of picking World Boxing Organization super lightweight king Terence Crawford as the young boxer can defeat him, as predicted by Floyd Mayweather Sr. On the other hand, according to the older Mayweather, World Boxing Council silver welterweight titleholder Amir Khan can't do it.

Mayweather Sr. told On the Ropes Boxing Radio about his thoughts and speculations if "Pacman" clashes with either Crawford or "King Khan" in early 2016 for his farewell fight.

"I think Crawford can beat Pacquiao. Amir Khan's got a glass jaw, if you look at him too long, he's gonna fall down. We'll see, but if Pacquiao hits Amir Khan good, Amir Khan's gone," said the father and coach of the unbeaten "The Money."

It may really be a challenge for the world-famous Filipino fighter to bring down the Omaha, Nebraska native. Crawford, who last crushed Dierry Jean on Oct. 24 at the Century Link Center in Omaha via a stoppage victory, remained unbeaten even after 27 fights, per BoxRec. At the same time, the WBO champ is only 28 years old or eight years younger than Pacquiao. Clearly, youth is his advantage.

"The Money" is also impressed with "Hunter." Mayweather Jr. told Fight Hype that he "really, really like that kid."

However, Mayweather Jr. has a piece of advice for the young boxer, which is to be cautious of Pacquiao. Based on his encounter with "Pacman" on May 2 at the MGM Grand Arena in Las Vegas, "The Money" can say that he "can fight."

"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," said the retired boxer.

"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," Mayweather Jr. added.

Even Top Rank CEO Bob Arum, who promotes both Crawford and "Pacman," believes that the younger boxer will be a difficult opponent for Pacquiao. Arum observes that he is skillful, clever and patient in dealing with Jean in October, Boxing Scene noted.

The 83-year-old promoter anticipates that a Pacquiao vs. Crawford showdown will be "hellacious type of fight" and that his veteran fighter will be getting what he is wishing for, which is to collide with the best "guy out there."

Does Crawford have enough skills to beat "Pacman?"