"He just has a different speed to him," said Hill, the Cincinnati Bengals running back who played college ball briefly with Mathieu at LSU. "He might not be the fastest guy out there, but how fast he plays the game of football, it's unreal. It's unmatched."
Mathieu's football speed will be tested by Hill's Bengals on Sunday night when they visit the Arizona Cardinals in one of the biggest games of the week. A case could be made that with Cincinnati (8-1) and Arizona (7-2) near the top of their respective conferences, this nationally televised game could be a Super Bowl 50 preview.
Games with that type of pregame acclaim often hinge on the success of playmakers like Mathieu. When the Bengals' offensive players break huddles Sunday, they certainly will want to know exactly where on the field the Cardinals safety is. If they lose track of him, it could be costly to their offense.
"He's a [Troy] Polamalu-type guy to where you've got to know where he is because he can game-change you in one play," Hill said. "He makes plays, he has a knack for the football and he loves playing. He just has that tenacious mentality every time he steps out there. I have a lot of respect for him."
Hill wasn't the only one to praise Mathieu this week. Bengals offensive coordinator Hue Jackson understands the impact Mathieu can have versus the pass.
"He's a student of the game," Jackson said. "He has tremendous ball skills, and he's a very good blitzer, more so than what people think. Because of his size you'd think, 'Oh my gosh, this guy shouldn't be doing this.' But he does it as well as anybody. They have a talented defense, and we've played a lot of good defensive football teams. We don't run from that."
The Bengals have already faced three of the top 13 defenses in the league -- including a 419-yard effort in an overtime win over the second-ranked Seattle Seahawks -- before going against Arizona's third-ranked unit Sunday. Also on the horizon are games against Denver (first) and St. Louis (sixth).
Mathieu has had a real impact on Arizona's defense throughout his three-year career, but this may end up being the best season the former third-round pick has had. Not only has he been fully healthy, but he already has a single-season career-high three interceptions. He's also forced a fumble, recorded a sack and registered 52 tackles. At his current pace, he will shatter his single-season tackles mark of 67, set his rookie year.
Something Mathieu and his Arizona teammates in the defensive backfield do well is pick off passes after one of them has deflected the ball into the air. Fellow safety Rashad Johnson leads the unit with four total interceptions, while Mathieu has three. Combined, the Cardinals have 14 interceptions, tied for the most in the league. Three of their pickoffs have been returned for touchdowns.
Bengals quarterback Andy Dalton, who was intercepted once last week against Houston, will try to keep from giving Mathieu and the other Cardinals a chance for more interceptions.
"You can control it to a certain extent with accuracy and putting the ball in the right spot," Dalton said. "Our guys have to make tough, contested catches. You can control it from the standpoint of knowing when to throw it in there, and when you do throw it, put it in the right spot."
The right spot is anywhere far away from Mathieu.