By Edward Chaykovsky

Veteran trainer and ESPN expert analyst Teddy Atlas believes UFC featherweight champion Conor McGregor would not at least five years of training, in boxing, to prepare for a fight with former five division world champion Floyd Mayweather Jr.

Mayweather, who retired last September with a 49-0 record, has been teasing about the possibility of coming back - and continues to name McGregor as the only opponent of interest. McGregor says he is interested, for the right money, to face Mayweather in a boxing match.

``He would need about five years, and I'm being very generous and conservative, of boxing training and experience to even entertain the thought of being competitive with any A-plus level boxer,'' Atlas said.

Atlas views the bout as one of biggest mismatches that can be made.

The well know trainer was even stumped when it came time to stamp down a game plan for McGregor, at least a game plan that would give him the best shot at victory.

``I wouldn't have him just attack like the caveman he tries to act like,'' Atlas said. ``Being aggressive would not be my advice -- he would simply bring on his demise quicker. And you don't attack a great counter puncher, especially when you are so crude.''

If he was training McGregor to counter Mayweather's defensive style, Atlas would expect a lifetime of training to overcome the odds.

``Years. Think in terms of Social Security," Atlas said.

As far as fight odds, the fight is such a mismatch in the eyes of Atlas - he says he would never even consider listing a line for a fight of this nature.

``None. If I were a betting oddsmaker, I would not list a betting line on this,' Atlas said.