Here's everything to know about Achilles tendinitis, including 49ers star Christian McCaffrey's injury and recovery timeline.

San Francisco 49ers star running back Christian McCaffrey could be out for six weeks or more due to his calf soreness and Achilles tendinitis, according

The latest speculation comes from NFL Network's Ian Rapoport, who believes McCaffrey is a "long shot" to play after missing San Francisco's 32-19 win over the New York Jets in Week 1 because of a calf injury and Achilles tendinitis.

49ers head coach Kyle Shanahan said running back Christian McCaffrey is dealing with both a calf injury and Achilles tendinitis, and he says the team will be cautious about not allowing McCaffrey to aggravate the injury.

"Nobody knows" when Christian McCaffrey will be ready to return from injured reserve, 49ers coach Kyle Shanahan said Sunday.

San Francisco 49ers running back Christian McCaffrey missed most of training camp and the entire preseason due to a calf strain and Achilles tendinitis,

When Christian McCaffrey went down, the 49ers could take solace in the fact that they had another versatile and dynamic weapon in Deebo Samuel. For the next two games, the 49ers will be without both as Samuel reported to work with a calf strain that coach Kyle Shanahan said would likely keep him out two weeks.

Kyle Shanahan will now be without two key offensive players in at least their next two fixtures against the Rams and Patriots, with McCaffrey also recovering from Achilles tendonitis.