It is common practice for the NFL and teams to stay in touch after games to report injuries, but there is no indication the league has launched a formal investigation into running back Christian McCaffrey’s report before the San Francisco 49ers’ season opener, a league source said Tuesday.

McCaffrey was officially listed as questionable before the game against the New York Jets. The accuracy of that classification was called into question Monday night after backup Jordan Mason, who rushed for 147 yards and a touchdown, said in a postgame interview with the broadcast team that he had been told he would start on Friday.

49ers coach Kyle Shanahan said after the game that he did not tell Mason he would be in the starting lineup, but told him to be ready because he expected him to play more. Mason declined to answer a question about his comments to the broadcast team in his postgame press conference.

McCaffrey is living day to day since he was unable to play due to his calf and Achilles tendon injuries, Shanahan said Tuesday, but had it been a playoff game, he could have played.

“You know, it’s not just a calf. It’s his Achilles tendon and, you know, the Achilles tendon has tendinitis and things like that come and go,” Shanahan said. “And when it starts to cause problems, you have to be very careful. Christian is pretty meticulous about things like that.”

“And if it was a playoff game, he made that very clear to me – he believes he could do it. But that’s the kind of thing you hear, and it’s not a playoff game, it’s Week 1. Especially when you’re dealing with the lower extremities like that, it was a tough decision, but hearing all the words and stuff made it easier in the long run.”

McCaffrey was only able to train to a limited extent prior to the game.

Shanahan described the calf/Achilles issues that kept him out of training camp as “similar” to the calf injury he suffered in Week 17 last season. He did not play in Week 18, although San Francisco rested most of its starters in that game, but returned for the divisional playoff game against the Green Bay Packers, running 17 times for 98 yards and catching seven passes for 30 yards.

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