SANTA CLARA (AP) — Donte Whitner realizes how different the San Francisco 49ers are now from the team that got whipped at Seattle in Week 2.

He’s still plenty bothered by that 29-3 loss to the rival Seahawks, and ready to play them again this Sunday at Candlestick Park and boost San Francisco’s position in the playoff picture.

“They embarrassed us last time we were there,” Whitner said. “We feel like we’ll be ready for the test, and it’s going to be a really, really big game and we’re looking forward to it.”

The reigning NFC champion Niners (8-4) need every win at this stage — and a victory against first-place Seattle could put them right back in the division title picture, too.

“As much as we want to play these guys and seek revenge, we have to keep our composure and approach the next game like it’s the same one we approached last week,” tight end Vernon Davis said. “We have to approach it like that.”

Considering the Seahawks have outscored the 49ers 71-16 in the last two meetings — both wins by Seattle at home — San Francisco’s players feel they have something to prove against their biggest NFC nemesis.

Whitner called for the defense to continue making key stands and he expects his unit to help decide how the season turns out. The offense is determined to keep doing its part now that things are clicking again for Colin Kaepernick and Co.

A 23-13 victory against St. Louis on Sunday gave San Francisco consecutive wins in commanding fashion following a two-game skid, and the offense is on a roll at the perfect time: With the December stretch run ahead, a time coach Jim Harbaugh insists is built only for the tough.

“I guess we will find out,” defensive tackle Justin Smith said. “We’ve got Seattle coming in here and they are sitting on top of the division. We are going to be ready for those guys and give them what we’ve got.”

Seattle was set to host New Orleans on Monday night, and everybody in San Francisco knows both the 49ers and Seahawks have changed plenty since that Week 2 matchup Sept. 15.

“We’ve changed and I’m sure they’ve changed in some ways,” Harbaugh said. “Not prepared to say in what ways.”

One way is clear for the 49ers. The passing game is making significant strides, and it helps that Kaepernick has his receiving corps healthy and intact at last. First Mario Manningham returned from a serious knee injury that prematurely ended his 2012 season and made him a Super Bowl spectator, then Michael Crabtree made his season debut Sunday six months after surgery for a torn right Achilles tendon.

Crabtree, the top wide receiver last season for San Francisco, had a pair of catches with a 60-yarder and forced the Rams defense to focus on both him and Anquan Boldin. Boldin had nine catches, while Davis caught a 17-yard touchdown pass for No. 50 of his career.

Boldin, Crabtree and Kaepernick said they would get together to watch the Saints-Seahawks game Monday night. These three believe they have more big games ahead.

“I don’t think we’re playing at our top level,” Boldin said. “I don’t think we’ve played our best football yet. We have some things we have to clean up.”

With division games down the stretch all the more meaningful, emotions run high. Harbaugh is fine with that, as long as his players make good decisions.

“I’ve never taken the revenge approach,” Harbaugh said. “Validation, we want to play well, we want to win. ... Your goal is to win the football game. That’s really all-consuming, you want to win.”