"You'll have to pardon Broncos defensive coordinator Don Martindale if he gets a little jumpy when folks talk about running backs these days.

Just look at the list the Broncos have faced this season:

Maurice Jones-Drew.

Chris Johnson.

Ray Rice.

LaDainian Tomlinson.

Darren McFadden.

Frank Gore.

Jamaal Charles.

Just for the record, Jones-Drew, Johnson, Charles and Gore are among the league's top 10 in rushing at the moment. McFadden is 12th, Rice is 14th and Tomlinson 16th despite splitting carries with Shonn Greene.

It doesn't get any easier for the Broncos' 31st-ranked run defense Sunday. Next in line is the Rams' Steven Jackson. Jackson is tied for eighth in the league in rushing - with the Steelers' Rashard Mendenhall - at 811 yards.

At 6-feet-2, 236 pounds, Jackson is also one of the biggest of the group and one of the most accomplished receivers out of the backfield. He led the Rams in receptions last season with 51, is third this season and has four seasons with at least 40 receptions in his career.

"That's a big man, that's a big man," Martindale said. "I told the defense you can relate him to a semi coming downhill with no brakes."

Jackson is the league leader in yards from scrimmage since the start of the 2006 season, and he is more difficult to handle these days because of the improved play of St. Louis' rookie quarterback Sam Bradford.

Bradford is still largely working just the short and intermediate routes in the passing game as the Rams continue to try and upgrade their roster. They don't have much depth on the outside at receiver because of injuries and a roster makeover."