Foster has not produced much for the 49ers. He has carried 37 times on the season for just 78 yards. And he has six receptions for 71 yards. Foster has fumbled twice, losing one of them. When asked if he's concerned with Foster's ability to hold onto the ball, Singletary answered, "Absolutely. Yes, I am."

Singletary said he believes Foster is trying to do too much when he gets his hands on the ball. "Frank Gore is in all the time, and then DeShaun gets a chance and he wants to show, 'Hey, I can do this,'" Singletary said.

If Gore is out of Sunday's game, the 49ers might promote running back Thomas Clayton from the practice squad.

PLAYER NOTES

-- WR Dominique Zeigler would return kickoffs Sunday if Allen Rossum is limited to punt returns due to his ankle injury.

--RB Michael Robinson might get a few more carries Sunday against the Dolphins in the likely event Frank Gore is unable to play. On the season, Robinson has 12 rushing attempts for 38 yards. A quarterback at Penn State, Robinson has taken about a dozen snaps this season in the 49ers' version of the "Wildcat" formation.

--TE Delanie Walker has done a commendable job on kickoff returns, filling in for injured Allen Rossum. Walker has averaged 20.5 yards on 12 kickoff returns with a long return of 35 yards three weeks ago against the Dallas Cowboys. Walker has just one reception the past three weeks. He had an apparent 28-yard touchdown catch nullified by a holding penalty.

--LB Tully Banta-Cain, who was a starter last season, has gotten little playing time on defense this season. However, Banta-Cain has made a contribution on special teams. He leads the 49ers with 15 tackles on special teams.

--LB Parys Haralson leads the 49ers with seven sacks on the season. Haralson has started seven of the team's 13 games. He has 42 tackles and 27 quarterback pressures.

--WR Isaac Bruce is coming on strong in the past three games, as he has overtaken running back Frank Gore for the team lead with 45 receptions on the season. Bruce ranks third all-time with 14,803 receiving yards, and fifth in lifetime receptions with 987.

--NT Aubrayo Franklin has been more productive in recent weeks, as he said he feels stronger after dropping 15 pounds in the offseason. Franklin has 63 tackles on the season with four quarterback pressures on the season.

--WR Josh Morgan is not listed on the 49ers' injury report for the first time since sustaining a groin strain on Nov. 10. Morgan will have to win back his starting job from veteran Bryant Johnson, who played well in Morgan's absence.

--QB Shaun Hill has performed very well whenever given a chance. In his career, which consists of seven starts, Hill has completed 64.6 percent of his passes with 15 touchdowns and five interceptions. His career passer rating is 97.3.

GAME PLAN: Mike Singletary says he is not as gung-ho about running the ball as he is about doing what is necessary to win football games. It just so happens that the best way for the 49ers to win games is to run the ball. That could change a little this week, depending on the availability of running back Frank Gore, who sustained a left ankle sprain in last week's game against the Jets. With Gore's status up in the air, the 49ers might have to turn to veteran running back DeShaun Foster. And that might mean that Singletary and offensive coordinator Mike Martz will want to put more responsibility on the right arm of quarterback Shaun Hill, who has performed admirably in just about everything the 49ers have asked of him since he joined the organization. The Dolphins rank in the middle of the pack in the NFL in team defense. They rank slightly better against the run, so Hill might be asked to throw the ball around the field on Sunday. Hill is at his best when there is the threat of the run. He has been good in play-action situations. Hill has developed a nice rapport in recent weeks with veteran wideout Isaac Bruce. Defensively, the 49ers will be tested against the league's 10th-ranked offense. The 49ers must stop the running of Ronnie Brown and Ricky Williams, and outside linebacker Parys Haralson has to step up with a big game to put pressure on quarterback Chad Pennington.

MATCHUPS TO WATCH: 49ers TE Vernon Davis vs. Dolphins OLB Joey Porter - Davis has turned into a much more valuable player as a blocker. Porter leads the NFL with 16.5.

49ers LB Patrick Willis vs. Dolphins RB Ronnie Brown: Willis leads the 49ers in tackles and is a sideline-to-sideline pursuer. Brown will try to keep the 49ers guessing out of the "Wildcat" formation.

49ers DE Justin Smith vs. Dolphins LT Jake Long: Smith has been one of the 49ers' top defensive players and rarely comes off the field. Long has started all 13 games after being the No. 1 overall pick.

49ers CB Nate Clements vs. Dolphins WR Ted Ginn Jr.: Clements returns this week after missing last week's game with a broken thumb. Ginn is tops among active Dolphins with 48 catches for 669 yards and a touchdown.

49ers C Eric Heitmann vs. Dolphins NT Jason Ferguson: Heitmann stonewalled Jets lineman Kris Jenkins last week. Now he'll face Ferguson, a 12th-year pro who has started 10 games this season.

49ers WR Isaac Bruce vs. Dolphins CB Will Allen: Bruce has emerged as Shaun Hill's favorite target. Allen has recorded a team-leading three interceptions this season.

49ers RB DeShaun Foster vs. Dolphins run defense: Foster is averaging 2.1 yards per carry as Frank Gore's backup. The Dolphins are allowing 96 yards rushing per game, which is in the middle of the pack in the NFL.

INJURY IMPACT:

-- RB Frank Gore (ankle) missed the entire week of practice, is listed as questionable and will be a game-day decision Sunday. "It's just going to be a game time deal," said interim coach Mike Singletary.

-- CB Nate Clements (thumb) was able to take part in limited practice this week and is listed as probable.

-- WR Arnaz Battle (foot) missed the full week of practice and is listed as questionable.

--S Dashon Goldson (knee) has missed six games with a torn MCL in his left knee, but he will be available for action Sunday against the Dolphins.

-- RS Allen Rossum (ankle) is listed as probable after missing two games. He was limited in practice all week. However, interim coach Mike Singletary said Rossum will return punts but "probably not" kickoffs.

--C Eric Heitmann (abdominal strain) missed practice time early in the week, but the 49ers expect him to be ready to start Sunday's game.

--CB Marcus Hudson (concussion) is questionable for Sunday's game.