49ers receiver Deebo Samuel strained a calf during Sunday's loss to the Vikings.

Coach Kyle Shanahan told beat reporters that Samuel will miss "a couple weeks."

"He told me he thinks he did it when he caught [a pass for a 2-yard gain]; I think it was like the third to last play [on offense]," Shanahan said, via David Bonilla of 49erswebzone.com. "They had a blitz down in the red zone. He caught the hot route, breaking in. He says he thinks he did it on that play. I think there was only like two or three plays after that play, though."

It's another blow for the 49ers, who placed running back Christian McCaffrey on injured reserve last week with a calf strain and Achilles tendinitis. McCaffrey won't return until at least Oct. 10. Rookie receiver Ricky Pearsall, the team's first-round pick, will miss at least two more games on the non-football injury list after being shot during an attempted robbery Aug. 31.

"When you lose real good players, it's always tough, but it happens all over the league, and it's a huge part of this league, and a huge part of this game," Shanahan said. "You've just got to deal with it."

Samuel made eight catches for 110 yards against the Vikings five for 54 yards in the season opener against the Jets.