Devon Alexander has brushed off criticism regarding his recent performances by insisting that he wasn't mentally right during his IBF welterweight title defeat to Shawn Porter.

The American lost his world belt by a unanimous verdict last December but he returned to winning ways with a victory over Jesus Soto Karass earlier this year.

Alexander faces Amir Khan in Las Vegas on Saturday night but ahead of their encounter, he believes that Khan doesn't have the ability to become a force at 147lbs.

During a pre-fight press conference on Monday, the 27-year-old said: "I wasn't thinking [against Porter]. I wasn't following a gameplan and I wasn't mentally in that fight.

"There was no reason. I perhaps took him lightly because I had beaten him in the amateurs but that's no excuse.

"I see nothing special in Khan. He is fast but I see nothing else. You have to have more arsenal than speed to compete at this level."

The winner of Saturday's bout could earn an opportunity to face Floyd Mayweather Jr in May.