SANTA CLARA – Coach Kyle Shanahan’s 49ers have another injury to worry about entering the bye week with their first-place, 6-1 record. It’s apparently not a major injury, however, even if it involves a marquee player.

Running back Christian McCaffrey’s leg injury, sustained on the opening drive of Sunday’s 29-20 loss at Atlanta, has been reframed as a mild hamstring strain, after initially being dubbed as a quadriceps issue.

“We’re pretty optimistic about it,” Shanahan said Monday in a conference call with reporters.

So optimistic that McCaffrey is expected to benefit from this week’s bye and be available for the 49ers’ next game, Nov. 8 against the Raiders.

“My leg just died on me and I tried to get it going for the whole rest of the game,” McCaffrey said postgame, after totaling 69 yards on the first drive but just 31 yards afterward as he tried to loosen up his leg.

As short-handed as the 49ers were in Atlanta with just four wide receivers in uniform, Shanahan is expecting post-bye returns from Mike Evans (Achilles), Deebo Samuel (hamstring) and Demarcus Robinson (ankle).

Defensive end Nick Bosa (calf) also figures to be available for that Raiders matchup after missing the past five games, and the 49ers’ defense also could welcome back safety Marques Sigel (ankle), defensive tackle C.J. West (knee) and linebackers Luke Gifford (hamstring) and Garrett Wallow (groin).

“All those guys have a chance after the bye but none are guaranteed,” Shanahan said. “It’s a big week of rehab for all of them.”

As for rookie wide receiver De’Zhaun Stribling, the 49ers are hoping for a December comeback after he required ankle surgery following the season-opening win over the Rams in Australia.

KICKER SITUATION

Kicker Eddy Piñeiro, after missing a point-after or field-goal attempt in five straight games, is not facing immediate competition.

“As far as I’ve heard, we don’t have any plans on that right now,” Shanahan said of potential tryouts.

Piñeiro missed a point-after attempt following a fourth-quarter touchdown Sunday, his fourth miss in 25 point-after tries this season; he is 6-of-9 on field-goal attempts after making 31-of-32 last season through the playoffs as Jake Moody’s Week 2 successor.

Shanahan said Piñeiro’s off-target trend did not influence a fourth-quarter decision to bypass a 41-yard field-goal attempt and instead go for it on fourth-and-10, resulting in a sack and no points. “I didn’t think a field goal was going to change much. I also thought we could get that first down,” Shanahan said. “So no, the kicking situation didn’t have anything to do with it.”

TRADE TALK

While general manager John Lynch and the personnel staff are discussing trade scenarios “seven days a week,” Shanahan said he will “watch stuff” over the bye week, too. The trade deadline is Nov. 10.

“If there’s stuff that makes sense to improve our team in any spot, we’d love for that to happen,” Shanahan said. “The obvious injury spots to us have been at receiver and D-line. We are getting a number of guys back at both positions, but that doesn’t exclude us from looking for help.”

KIRK’S DEBUT

Christian Kirk played 20 of the 66 offensive snaps in his 49ers’ debut, and although he wasn’t targeted, he did impress Shanahan, who said; “He did a good job in separating and running his routes right. He played really well in the run game too. I thought he blocked well and it was a good game to keep working to get his feet back under him, but I thought it was a good step in the right direction.”