Back injury will keep Patriots' Maroney on sideline

The New England Patriots will be without leading rusher Laurence Maroney for Sunday's game against the Miami Dolphins, downgrading their rookie tailback to "out" on Saturday night because of a back injury.

Laurence Maroney Maroney

New England's first-round choice, and the 21st player selected overall in the 2006 draft, Maroney has been bothered by the recurring back problem for a few weeks. The former University of Minnesota standout has played as the backup to veteran Corey Dillon in all 12 games, but has 624 yards and three touchdowns on a team-high 155 rushing attempts.

Maroney's rushing yardage is the second most in the NFL by a rookie, trailing only Indianapolis Colts' first-round choice Joseph Addai.

The loss of Maroney for Sunday will also affect the Patriots' special teams, as he is the primary kickoff return man, and ranks second in the league with an average of 28.7 yards on 27 runbacks.

In the absence of Maroney, it's believed the Pats will use a combination of Kevin Faulk, Patrick Pass and Heath Evans, depending upon game circumstances, as the backup tailbacks.

Besides Maroney, the Patriots ruled wide receiver Chad Jackson (groin), right offensive tackle Ryan O'Callaghan (neck) and safety Rashad Baker (leg) out for Sunday's game. Jackson is the team's second-round draft choice and O'Callaghan has been a part-time starter.

New England also placed linebacker Don Davis (knee), one of the team's top special teams performers, on injured reserve, ending his season, and released offensive lineman Gene Mruczkowski. The Pats promoted wide receiver Kelvin Kight and cornerback Antwain Spann from their practice squad.

Len Pasquarelli is a senior NFL writer for ESPN.com.