Tight end Vernon Davis is anticipating changes, noting: "They're definitely going to have to make changes. We've got Crabtree back and have pretty much all our weapons. It's going to be exciting and interesting to see the changes they make to stop us. They can't leave us one-on-one the whole time."

Davis had just three receptions for 20 yards, and Anquan Boldin had only a 7-yard catch in the Sept. 15 loss at Seattle.

Crabtree had four receptions and no touchdowns in each of last season's games with the Seahawks, but he made a 41-yard catch that keyed a Dec. 24, 2011, win at Seattle.

"I can't wait to go out there and do what I can do," Crabtree said. "This week is a big week for us. With that (11-1) record, you're supposed to be the top team in the NFL. We'll see on Sunday. It gets you hyped. Now it's about me calming down. This is my second game. I can't wait to go and play."

Asked about a potential matchup with Seahawks cornerback Richard Sherman, Crabtree said this game is "not about one person or two people."

Staley wants to play Sunday

Left tackle Joe Staley vowed to play Sunday after practicing a second straight day with a Grade I sprain of his right knee's medial collateral ligament. "It still hurts. It's stiff. But it's something I can play through," Staley said. He's officially listed as questionable, and Harbaugh wants to see how Staley feels Saturday.

Blakeman's motley crew

Clete Blakeman, who's been involved in recent officiating controversies, will be Sunday's referee. He failed to call a penalty on Steelers coach Mike Tomlin for his sideline interference on Jacoby Jones' kick return on Thanksgiving. Only 2? weeks ago, Blakeman waved off a potential pass-interference penalty at the end of the New England Patriots' loss in Carolina.

Blakeman didn't go unnoticed in his past two 49ers games. Last season, he and his crew allowed 79 seconds to improperly run off the clock in the 49ers' 24-24 tie with the St. Louis Rams. In 2010, Blakeman ejected defensive tackle Justin Smith for making contact with umpire Garth DeFelice in a 34-7 loss at San Diego. Although Blakeman deemed Smith's act "intentional," the league did not fine Smith for his actions.

The 49ers and Seahawks combined for 22 penalties and 205 penalty yards in their Sept. 15 meeting.

Peek at the medical files

Cornerback Tarell Brown said his rib injury is "something I'm going to have to fight through the rest of the season." Tramaine Brock is expected to start a third straight game in place of Brown.

Left guard Mike Iupati still has not practiced since spraining his left knee Nov. 17. He is listed as questionable, and Adam Snyder likely will start in his place.

The Seahawks ruled out wideout Percy Harvin (hip) and cornerback Brandon Browner (groin).

Also questionable for the 49ers are wideouts Mario Manningham (knee) and Jon Baldwin (calf), tight end Vance McDonald (ankle) and linebacker Dan Skuta (foot).

Can't play down this rivalry

Harbaugh didn't pump up the 49ers-Seahawks rivalry more than any other, noting: "They all feel like a rivalry every single week. That's why I always thought it's a sprint, not a marathon."

Staley, however, said the 49ers-Seahawks rivalry has "gotten worse" in recent seasons for a "variety" of reasons. "I don't have a magic answer why it's intense, but it is," Staley said.

Lockette catching on

Former 49ers wideout Ricardo Lockette has had one catch in three of the Seahawks' past four games, including a 33-yard grab Monday night against New Orleans.