Two days before the biggest fight of his career, Amir Khan's trainer Virgil Hunter has conceded his fighter lacks "killer instinct".
The 29-year-old will on Saturday challenge WBC middleweight champion Saul Alvarez, and remains the significant underdog for more than just the fact he is stepping up in weight.
Saturday's fight at Las Vegas' new T-Mobile Arena will be at a catchweight of 155lbs, two divisions beyond welterweight where Khan is established, and comes against a fighter considered among the world's best.
Few give Khan a chance of defeating Mexico's Alvarez, and it is accepted his greatest chance of victory comes in using his superior speed and avoiding exchanges, but in the same week Khan has accepted he lacks the power to hurt the champion, Hunter has spoken of his belief he lacks a trait Alvarez is widely considered to have.
"Amir doesn't have that type of killer instinct that Miguel Cotto has," said Hunter, one of the world's leading trainers, when asked about Alvarez's past fight against Puerto Rican Cotto. "If he had that type of killer instinct we could really know if his punch was in comparison with (Cotto's).
"You can't call up killer instinct, that has to be you. That has to be in you a long time ago you know. You see kids come in the gym, they want to hurt somebody: right away, you know that's killer instinct.
"If they get beat up, they're right back the next day, with a vengeance, like 'I'm going to get you'. I've seen that, that's a trait."
Hunter is largely responsible for the significant improvement in Khan's defensive flaws since he was appointed his trainer in 2012 following Khan's split from the respected Freddie Roach.
He spoke earlier in the week of how impressed he was at Khan's attitude and reaction to the setbacks suffered in successive defeats before they linked up, and though few expect Khan to hurt Alvarez on Saturday, Hunter insisted his body punching is comparable with the very best.
"I'll tell you this much: his left hook to the liver, I'll match you with anything," said the American, who also trains the great Andre Ward.
"The one he put (Marcos) Maidana down with, he can hit to the body - he can really hit to the body - and he's got a 'body-whip' effect to his punches.
(And) he has competitiveness (instead of a killer instinct).
"Competitiveness, done right, can sort of put you in the same class, but I don't advise him to trade punches with (Alvarez), because he's giving up too much size."