SAN FRANCISCO (AP) — Michael Crabtree produced a career season a year ago and helped lead the San Francisco 49ers back to the Super Bowl for the first time in 18 years as Colin Kaepernick’s top target.

Now, the wide receiver is expected to make his long-awaited season debut Sunday against St. Louis, barely six months after he underwent surgery for a torn right Achilles tendon.

The reigning NFC champion Niners (7-4) made significant strides in their passing game during Monday night’s 27-6 win at Washington, and now hope to build on that — with or without Crabtree back in the mix. He sure could provide a boost as San Francisco makes a push for the playoffs.

St. Louis certainly knows how dangerous Crabtree can be. He had five catches for 70 yards and a 14-yard touchdown the last time the Rams visited Candlestick Park in 2012 and left town with the NFL’s first tie in four years.

Against the Redskins on Monday, Anquan Boldin made five receptions with two touchdowns, while Vernon Davis had four catches with a TD. Mario Manningham made four catches in his third game back after recovering from knee surgery late last season. Boldin and Crabtree have yet to play together.

“Definitely some good things,” coach Jim Harbaugh said. “We hit some big plays and that generated offense and got us going.”

St. Louis (5-6) tries for its first three-game winning streak.

Here are a few things to watch for when the division rivals connect on Sunday:

Kaepernick’s progress

Kaepernick quieted all of his critics for at least five days. The third-year pro, who just hit the one-year mark since becoming San Francisco’s starting quarterback, bounced back from consecutive losses with an emphatic performance at Washington. He threw for 235 yards and three touchdowns without an interception to finish with a career-best passer rating of 134.5 against the Redskins. The 49ers moved to 11-0 with Kaepernick as the starter in games he posts a passer rating of 90.0 or better.

49ers’ playoff picture

At 7-4 and tied with Arizona for second place in the NFC West, the 49ers realize full well they have little margin for error to secure a return trip to the playoffs after their Super Bowl run of 2012. Especially with the division rival Seattle Seahawks (10-1) coming to the Bay Area on Dec. 8 after whipping the Niners 29-3 in Week 2. Kaepernick, for one, doesn’t believe momentum plays into it at this stage of the season.

“Game to game,” he said. “Have to win.”

Pass-rushing Rams

Robert Quinn and that swarming St. Louis defense have been creating havoc for opposing quarterbacks, and the defensive line has scored touchdowns in each of the past two games.

Menacing defensive end Quinn has been a pain for quarterbacks with 13 sacks, 35 tackles and six forced fumbles. Fellow defensive end Chris Long returned a fumble for a touchdown against Indianapolis leading up to the bye week, then Quinn sacked and stripped Bears quarterback Josh McCown, recovered the fumble and scored against the Bears.

And Kaepernick has shown his vulnerabilities in recent weeks.

The 49ers offensive line has surrendered 11 sacks the past three games, nine in back-to-back losses against Carolina and New Orleans.

49ers left tackle Joe Staley has the job of lining up opposite Quinn and trying to keep him away from Kaepernick.

“He’s just having a lot of success this year getting to the quarterback,” Staley said. “The thing I see most improved — his pass rush has always been there — this year he’s doing a great job in the run game as well.”

Staley is having another stellar season himself, one he feared might be in jeopardy after he sprained his left ankle in the game at St. Louis in September. Staley initially feared he had broken it.