HOUSTON -- Heading into their matchup against the Washington Redskins on Sunday, Houston Texans head coach Bill O'Brien knows the importance of stopping the run early, especially when facing running back Adrian Peterson.

"If he gets into the secondary, you're in trouble," O'Brien said. "Because that's like a train rolling down the tracks. He's one of the best to ever play the game, so it's going to take everything we have to have a chance to stop him."

This season, Peterson has run for 672 yards and four touchdowns on 155 carries. The 33-year-old's average of 74.7 rushing yards per game ranks eighth among running backs this season.

One person who is familiar with how good Peterson can be is Tyrann Mathieu. The Texans safety was teammates with Peterson for six games in Arizona last season and noted that the veteran running back's presence made a big difference with the Cardinals.

"I spent some time with AP [Peterson] in Arizona last year," Mathieu said. "He's a great running back. Just his name alone speaks for itself. I think what he's been able to do this season -- really going into Washington and trying to give those guys an identity as far as running the football with their running back going down early in the year. He's doing a great job for those guys. We have a big challenge Sunday."

Mathieu said it's not enough to just stop Peterson early, reminding that it's important the Texans' run defense stays on the running back all game. Houston has had success against the run this season, allowing an average of 92.9 rushing yards per game -- sixth in the NFL.

"He loves contact," Mathieu said. "I think he feeds and gets better as the game goes on. We've got to do a great job obviously of starting fast, getting hats on him and then finishing the game."

When Peterson was a free agent in the past two offseasons, he expressed interest in playing for his hometown Texans. O'Brien said he has "been around [Peterson] a couple times" and that the running back is a "great guy."

"We talk about everybody over the years that are free agents, and he was one of the guys," O'Brien said. "Maybe the timing wasn't right. I think it's all about timing and fit, and maybe the timing wasn't right. It had nothing to do with anything other than that. He's a fantastic player."

The Texans got a close look at Peterson last season when he was with the Cardinals. Last November, Houston held Peterson to 26 yards on 14 carries and one catch for 13 yards. Although the Texans had success against the running back last November, O'Brien cautioned that the offense that the Redskins are running this season is different than Arizona's last season.

"I think a lot of that has to do with playing good fundamental football," O'Brien said. "We better be ready to go, because he has 600-plus yards rushing.

"He's big. He's got great vision. He's still got great speed. He's got excellent ability to cut. Great balance. He catches balls out of the backfield. ... He's one of the best running backs to ever play the game."