SANTA CLARA -- If big plays aren't available to carry the 49ers past the Green Bay Packers this time around, can success be attained in short-yardage situations?

The 49ers (12-4) failed to convert on four short-yardage plays in last Sunday's win at Arizona, including loses of minus-5 yards on each of their third-and-1 rushing attempts.

"Certainly after last week, we need to improve there," offensive coordinator Greg Roman said. "It's an area we've been really good at this year."

That's true on second-and-1 runs (12-of-17 conversions) but not on third-and-1, wheree they're 9-of-17 for a 52.9-percent success rate that ranks fourth-lowest in the league. On third-and-2, they've converted 1-of-6 runs, but 6-of-9 passes.

Impacting their short-yardage game is the loss of fullback Bruce Miller to a fractured scapula Dec. 15. Roman, however, said Anthony Dixon and Will Tukuafu have fared well in Miller's absence. Dixon had two carries last game: a 5-yard loss on third-and-1 and no gain on fourth-and-1.

In their past two meetings with the Packers, the 49ers have won behind a bevy of big plays, with 10 going for at least 17 yards in each game. In the season opener, the 49ers converted all six times they needed one or two yards for a first down, and twice they produced touchdowns (Frank Gore run, Vernon Davis reception).