SANTA CLARA -- The 49ers had reason to give thanks Thursday: Their full complement of wide receivers was catching passes at practice, including Michael Crabtree and Mario Manningham.

Sunday against the visiting St. Louis Rams could mark the first time this season that Crabtree and Manningham, the team's top two wide receivers in 2012, are on the field together. Crabtree, who tore his right Achilles in May, hasn't played all season. Manningham, who tore knee ligaments in December, returned Nov. 10.

"Nice to see those guys out there," offensive coordinator Greg Roman said after practice, which was closed to the media. "It takes on a different dimension."

Crabtree left the locker room without comment, declining questions.

San Francisco 49ers’ Michael Crabtree (15)runs for a touchdown in the third quarter of Super Bowl XLVII against the Baltimore Ravens on Sunday, Feb.
San Francisco 49ers' Michael Crabtree (15) runs for a touchdown in the third quarter of Super Bowl XLVII against the Baltimore Ravens on Sunday, Feb. 3, 2013, at the Superdome in New Orleans. The Ravens beat the 49ers 34-31. (Jim Gensheimer/Bay Area News Group Archives)

Roman said it's "fair" to assume that Crabtree will be eased back into action and won't play every snap. Crabtree carries a two-inch scar above his right heel but isn't expected to require additional equipment to support his Achilles. Or, as Roman put it: "He won't be out there in a ski boot."

Presuming Crabtree is activated, the 49ers are likely to deactivate Jon Baldwin, who has zero receptions since Oct. 13 and doesn't play special teams.

Manningham, who missed practice Wednesday to rest his knee, is coming off his best game of the season, having caught four passes for 45 yards in Monday's 27-6 win at Washington. Rookie Quinton Patton also is practicing this week for the first time since fracturing his right foot in the Sept. 26 win at St. Louis.

The 49ers rank last in the league in passing yards per game, and only two players have touchdown catches: Vernon Davis (nine) and Anquan Boldin (five). The last time the 49ers had only two receivers catch touchdowns was 2005 (Brandon Lloyd and Arnaz Battle) when they finished 4-12. In their Super Bowl-winning seasons, the 49ers, on average, had seven receivers catch touchdowns.

"We all feel that the more guys we can get involved, that's something we'll do," Roman said.

In the absence of Crabtree, who caught 85 passes for 1,105 yards last season, Boldin has become the go-to guy for quarterback Colin Kaepernick, especially on third down. Boldin ranks fourth in the NFL with 23 third-down receptions. Crabtree had 30 last season.

Coach Jim Harbaugh praised Boldin as a great player having a great season, crediting his "ability, his awareness at all times, savviness, great catching ability. Just strong, strong player. Strong catcher."

Roman said it'll be a bonus if Crabtree can "balance out the field" with Boldin, just as the team envisioned when it traded a sixth-round draft pick to Baltimore for Boldin in March.

  • Adam Snyder will start for the second straight game in place of left guard Mike Iupati, who missed the first game of his four-year career Monday with a sprained left knee.

  • Linebacker NaVorro Bowman (knee, shoulder) and defensive tackle Justin Smith (shoulder) returned to practice after missing Wednesday.

  • Cornerback Tarell Brown (ribs), defensive tackle Ray McDonald (ankle) and tight end Garrett Celek (hamstring) stretched with their teammates before doing individual conditioning.

  • Defensive coordinator Vic Fangio praised cornerback Tramaine Brock for making a critical tackle at the end of Monday's first half. New nickel back Eric Wright played better, "but his best football is ahead of him," Fangio said.

  • Rams leading rusher Zac Stacy (concussion) returned to practice in a limited capacity after missing Wednesday's session.

  • Tight end Vance McDonald made strides Monday night, said Harbaugh, noting that the rookie "had some struggles in the run game" Nov. 17 at New Orleans. "But, he has been the kind of guy that learns from his mistakes and gets them corrected, gets them fixed," Harbaugh added. "It's going to be a bright future for him. I'm still convinced of that." McDonald hasn't had more than one catch in any game, and he has eight receptions for 119 yards and no touchdowns.

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    Sunday's game

    St. Louis (5-6) at 49ers (7-4), 1:05 p.m. FOX