ST. LOUIS — Three weeks ago, Kenneth Darby was part of the Atlanta practice squad. On Sunday, he'll be an NFL starter.

St. Louis Rams coach Jim Haslett on Friday made Darby the starter for the game against the Jets in New York. Steven Jackson will sit as he continues to recover from a quad injury suffered in a game on Oct. 19 against Dallas.

Darby has two carries for 9 yards in his NFL career, but believe he's prepared as St. Louis (2-6) tries to snap a two-game losing streak.

"I'm ready for it," Darby said. "I've been preparing all week for it. "I know I'm ready. This is a great opportunity for me and I want to take full advantage of it. This opportunity I'm getting this Sunday is very rare for most guys, especially guys of my caliber."

Jackson was unable to practice Friday, a day after Haslett said if he couldn't work out he wouldn't play against the Jets (5-3).

"He didn't practice so he won't go this week," Haslett said.

Samkon Gado, signed by the Rams on Tuesday, will be Darby's backup. Gado was working as an assistant in the emergency room at Providence Hospital in Columbia, S.C., and had been out of the league since not being tendered a contract as a restricted free agent by the Miami Dolphins in the offseason.

Antonio Pittman, bothered by a hamstring, practiced Friday and will be available. Another backup running back, Travis Minor, is still dealing with a concussion and will not play.

The Rams signed Darby off the Falcons' practice squad Oct. 15. He was a seventh-round draft choice in 2007 by Tampa Bay and played in one game for the Buccaneers, when he also had two receptions for 16 yards. He has had 12 practices with the Rams.

Jackson said he will help Darby and Gado all he can.

"The offense is really complicated and it is going to take all the other 10 guys helping the young guys out," Jackson said.

It's a tall task. The Jets' defense, anchored by tackle Kris Jenkins, ranks fourth in rushing defense, allowing 76 yards per game.

Gado said he is glad to have the chance after bouncing around the league since 2005 with Kansas City, Green Bay, Houston and Miami. He said he was training six times a week in case a team called.

"This is the nature of the beast and you have to be ready when your number is called," he said.

Linebacker Chris Chamberlain missed practice Friday with the flu. DE Eric Moore (spine) is out for Sunday.