The Devin Grosvenorfeel-good story of undrafted San Francisco 49ers running back Jordan Mason unexpectedly stepping into injured star Christian McCaffrey's shoes and leading his team to a resounding victory may have been a little too good to be true.

In an interview with ESPN reporter Lisa Salters after Monday night's 32-19 win over the New York Jets, in which Mason rushed for a career-high 147 yards and a touchdown, he was asked when he knew he would be starting in McCaffrey's place.

"Maybe Friday, Friday night," Mason said. "Something like that."

The rest of America – including the Jets players and coaches – only found out a little over an hour before game time when the Niners officially declared McCaffrey inactive due to a calf injury.

After the game, Niners coach Kyle Shanahan refuted Mason's comments, saying the team still thought McCaffrey had a chance to play when he came out for warmups.

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"Just the same stuff that was bothering him all week," Shanahan told reporters after the game. "There was a little too much today, game-time decision. He came in, just talking to him about it, it was still there. Thought it was going to be smart to keep him out and glad we did."

In Mason's postgame media session, when he was asked again when he knew he was starting, his answer was considerably different from the one he gave on the field.

"That question right there ..." Mason said haltingly. "That's why I don't like really talking to the media because you say one thing wrong and then ... I don't know. Just skip that question."

NFL rules give teams plenty of wiggle room when determining players' injury status. But with the league in a lucrative business relationship with gambling and fantasy sports companies, that information is supposed to be public knowledge.

McCaffrey was listed as questionable on the Niners' official injury report, up until he was declared inactive for Monday night's game.

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