Dallas Cowboys head coach Jason Garrett has insisted that running back DeMarco Murray's past success against the St Louis Rams counts for very little heading into their week-three clash.

Murray ran for a franchise record of 253 yards against the Rams in 2011, and followed that up with a 175-yard performance in the 2013 campaign.

However, Garrett is adamant that the Rams are a very different side from last year and feels that success for Murray in the ground game is not guaranteed.

"I think you've got to be really careful of going back and saying, 'Boy, he plays great against these guys,' " Garrett told reporters.

"Well, these guys aren't necessarily the same guys he's played against in the past. But, he's certainly playing well right now. We've run the ball well the first couple weeks, and he's been a big part of it."

Murray has ran for 285 yards and two touchdowns this season.