Arizona Cardinals quarterback Carson Palmer has hailed the performance of rookie cornerback Tyrann Mathieu in training camp.

Mathieu was drafted by the Cardinals in the third round of the 2013 draft after character concerns and reported drug use during his days at Louisiana State University dropped him down the teams' boards.

Palmer told reporters: "Tyrann is getting his hands on a lot of balls. He's so quick and explosive in and out of breaks and reading concepts and knowing coverages and weaknesses in where we're trying to throw the ball."

Arizona begin their pre-season against Green Bay Packers on Friday.