With the Niners up 23-19 in the fourth, #1 overall pick Kyler Murray made a play with his legs going 22 yards for the scamper touchdown to give the Cardinals a 26-23 lead.
Under a minute to play, San Francisco's Jimmy Garopolo connected with Jjeff Wilson Jr. to give SF the lead again.
With 0:31 seconds to play, Murray connected with Johnson for one of his two catches on the day, but he would fumble and the 49ers would recover.
He was visibly upset in the locker room, but ABC 30 caught up with him to ask what it's been like to play with guys like Larry Fitzgerald and Kyler Murray in his first year in the league.
"Just learning from him, he's one of the best in the game so I'm just going to keep learning and keep trying to develop to be a guy like him," Johnson said. "Playing with a guy like Kyler Murray, he's a dynamic player and can make plays with his feet so it's only going to get better."
The Niners keep pace with the Patriots improving to 9-1 on the season. They'll be back in action Sunday to host the Green Bay Packers.
KeeSean Johnson will return to Fresno next Saturday with the game against Nevada and will join Aaron Judge as honorary captains at the game.