CB Nate Clements and LB Takeo Spikes return to Buffalo, where they played the best Football of their careers. Clements is the 49ers' best cover corner and gets assigned to the opponents' best receiver. That means he'll see a lot of Bills WR Lee Evans today. Spikes is still a solid player with a good feel for the game and an excellent nose for the Football (three interceptions, four passes defensed). The Clements-Evans matchup will be intriguing. Clements will probably try to be physical with Evans, pressing him off the line of scrimmage. But Clements takes chances, which allows receivers to get behind him. If he gambles too much, he'll get burned like he did against Dallas' Terrell Owens (213 yards) last week.

2. Back in the saddle

Bills QB Trent Edwards found the perfect cure for his ailing game last week: a bad defense that couldn't rush the passer or cover his receivers. San Francisco is better defensively than the Chiefs, but the 49ers have been very generous in giving up a lot of passing yardage. Even if Clements neutralizes Evans, Edwards will have plenty of other options. Slot WRs Josh Reed and Roscoe Parrish may be able to pick on nickel CB Keith Lewis, who lacks speed and can be beaten deep. Edwards hasn't been sacked in two games. If the 49ers don't generate a consistent pass rush, particularly from DE Justin Smith and OLB Parys Haralson, it may be a long day for their defense.

3. All-purpose threat

RB Frank Gore is the centerpiece of the 49ers' offense. A powerful runner with breakaway speed, Gore has rushed for 860 yards (4.5 per carry) and is the team's leading receiver with 36 catches. His 1,191 total yards from scrimmage is tied for third in the NFL. Imagine what Gore could do if he got more touches. He has had 20 or more rushing attempts only twice this season as the 49ers usually abandon the running game when they fall behind or teams crowd the line of scrimmage to stop Gore. With the possibility of bad weather today, Martz needs to establish Gore even if the Bills play eight men in the box as expected.

4. The Bills' 1-2 punch

Led by Marshawn Lynch and Fred Jackson, the Bills' running game has come to life, averaging 178.5 yards in the last two games. The majority of those yards have come after contact. The offensive line has helped, too, as it is playing with a physical mentality it didn't display in previous games. Lynch and Jackson are built for late-season games in inclement weather and figure to be featured a lot today. The 49ers aren't bad against the run and ILB Patrick Willis is the reason. A rookie All-Pro pick last season, Willis leads the 49ers in tackles (129) and passes defensed (10). The defense is designed to protect Willis so that he can use his speed to make tackles all over the field. But the D-line doesn't occupy blockers well, which means Willis has to work harder to make plays.

5. The Mad Scientist

San Francisco 49ers offensive coordinator Mike Martz is known for his creative schemes and love for the downfield pass game. It has allowed the 49ers to lead the NFL with 44 20-yard pass plays. But that approach comes with a price as the 49ers have allowed 40 sacks (second in the NFL). Look for the blitzing Bills to get after QB Shaun Hill, who is coming off a 303-yard effort last week. When given time, Hill has good receivers to throw to. Bryant Johnson has the size (6-foot-3) to be effective on slant passes. Isaac Bruce, a 15-year vet, has lost a step but he's still very crafty (34 catches for team-high 558 yards and five touchdowns). Underachieving TE Vernon Davis has three catches in the last three games, but he has a speed advantage against the Bills' safeties. Gore presents a big mismatch against the Bills' linebackers.

Prediction

Their playoffs hopes already compromised, the Bills can't afford a letdown against the 49ers. Bills, 27-17.