As the 49ers began preparing Monday for their playoff showdown with the Green Bay Packers, cornerback Carlos Rogers headed for an MRI exam on his injured right hamstring.
That means the 49ers might be doing a secondary shuffle before facing a Packers passing attack that ranked sixth in the NFL -- even without quarterback Aaron Rodgers for much of the season.
The 49ers bolstered their defensive backfield Monday by signing cornerback Perrish Cox, although coach Jim Harbaugh said the team planned to make that transaction even before Rogers went down late in Sunday's victory over the Arizona Cardinals.
Harbaugh sounded undaunted by any hurdles Monday, calmly defusing questions about Rogers' injury, Lambeau Field's chilly weather and the possibility of needing three consecutive road victories to reach the Super Bowl.
"Being in the playoffs is a chance at the ultimate chance," the coach said. "Our guys have been in that position before, so they understand the magnitude of the challenge."
The fifth-seeded 49ers (12-4) will play the fourth-seeded Packers (8-7-1), a team they have defeated three consecutive times, including last year's playoffs when quarterback Colin Kaepernick ran wild for 181 yards.
That game was at Candlestick Park. The forecast for Green Bay on Sunday calls for a high of 19 degrees.
"We'll keep our bodies warm by playing hard," Harbaugh shrugged. "Football weather is any weather."
Since Harbaugh took over as coach in 2011, the 49ers are 17-7 on the road. That .708 winning percentage ties the Denver Broncos for the best in the NFL during that span.
The 49ers went 6-2 on the road this season, losing at Seattle (Sept. 15) and New Orleans (Nov. 17).
This time, they will go against a Packers team coming off a rousing victory to clinch a playoff spot. Rodgers, returning from a broken left collarbone, threw for 318 yards, including a 48-yard touchdown to Randall Cobb with 38 seconds left.
Harbaugh's review of how the three-time Pro Bowl passer looked?
"Very good," he said, and left it at that.
With Rogers ailing, Harbaugh acknowledged that the 49ers might have to tinker with their secondary. Veterans Tarell Brown and Tramaine Brock would start, with Eric Wright covering the slot receiver in nickel situations.
Cox spent the early part of this season with the 49ers before being signed by Seattle. The Seahawks released him Friday, and Harbaugh said that's when the 49ers saw an opportunity to bring him back.
The 49ers pass defense has looked vulnerable in recent weeks, surrendering 407 yards to Arizona's Carson Palmer and 348 to the Atlanta Falcons' Matt Ryan.
"We all want to improve," Harbaugh said when asked about the pass defense. "No. 1, win the game. Just win. And then always looking to improve any phase of the game you can."
Under that scenario, the 49ers might not head home from the Midwest. Harbaugh left open the possibility of practicing in Youngstown, Ohio, during the week, just as the 49ers have on previous occasions when they wanted to cut down on cross-country travel.
"I've given it some thought," Harbaugh said. "I'll keep you posted."
Staff writer Cam Inman contributed to this report.
49ers (12-4) at Green Bay (8-7-1), 1:40 p.m. FOX