Devon Alexander has warned Amir Khan that he should not be underestimating him, as he has the power to knockout the British boxer in their welterweight showdown in Las Vegas.

The 27-year-old American has won half of his fights through knockout, and said that rather than looking ahead to a potential 2015 bout with Floyd Mayweather, Khan should focus instead on the threat he represents when the two fight on Saturday.

Saturday's clash will be Khan's first fight since defeating veteran American Luis Collazo in his welterweight debut in May.