49ers' Jordan Mason 'Mad' At Reporters After Confusion Over McCaffrey Injury Status

San Francisco 49ers running back Jordan Mason had a breakout performance on "Monday Night Football," but he was anything but pleased after the game ... and it's all thanks to confusion over comments he made about Christian McCaffrey's injury status.

Mason -- an undrafted free agent out of Georgia Tech in 2022 -- made the most of his opportunity as RB1 after the "Madden 25" cover athlete was ruled out with a calf and Achilles injury ... rushing for 147 yards and a touchdown against the New York Jets in his first career start.

After the contest, he suggested to a sideline reporter he was informed Friday night he'd be the starter come gameday ... which raised eyebrows as CMC was only listed as inactive less than two hours before kickoff.

It was a shocking statement, as teams are required to be transparent about injury reports to maintain the integrity of the sport ... and a ton of money in fantasy football and legalized betting is on the line with each matchup.

When Mason was asked again about when he knew he'd be the starter in his postgame presser, he expressed his frustrations over the situation.

"That question right there is why I'm mad," Mason said. "That's why I don't like really talking to media 'cause you say one thing wrong and then, you know ... I don't know. Just skip that question."

Niners head coach Kyle Shanahan, on the other hand, was adamant the team only decided Monday afternoon CMC wouldn't play ... as his injury status changed from day to day.