The 6-foot-7 small forward from Santa Ana (Calif.) Mater Dei went off for 33 points, 14 rebounds, 4 steals and 2 blocks as the Oakland Soldiers came from behind to fend off Abdul Malik Abu and Expressions Elite, 67-64.
Johnson's 33 points -- he also went 3-for-5 from the arc -- accounted for almost half of his team's offensive output.
"He'll be one-and-done," one Division 1 head coach told SNY.tv, likely summing up the feelings of just about everyone in the gym.
Johnson, who was double-teamed for much of the game, said his goal is to help defend the Soldiers' Peach Jam title, won last year when current Arizona freshman Aaron Gordon, then bothered by a back injury, helped beat Andrew Wiggins and CIA Bounce in the championship game.
"If we can do this, I think we'll have a chance to win Peach Jam," Johnson said.
On one series, Johnson dunked one-handed and posed right in front of Wisconsin coach Bo Ryan and then turned around, raced downcourt and swatted a shot attempt on the other end.
Asked about the play, he said with a laugh, "I don't know who Bo Ryan is, by the way."
He added: "I can do that...That's one of those plays I can make and the block just happened to be there. He kind of threw up a weak layup so I had to [throw] it out."
Johnson has recently said he will take five officials to Kansas, Kentucky, Florida, Oregon and Arizona while local programs UCLA and USC will get unofficial visits.
Kentucky has offered Houston Hoops wing Kelly Oubre, according to the player and his father, but Johnson still feels he is their No. 1 priority at small forward.
Kentucky coach John Calipari was courtside for this game and had a great seat for the block.
"I'm the only person that was offered by Kentucky at my position so that's a big deal for me," he said of Kentucky. "So just kind of realizing that kind of made me think about that a little bit more."
He's also excited about heading to Big Blue Madness in October.
"That's supposed to be the biggest show ever," he said. "I talked to Cliff [Alexander], Cliff went last year. I have a couple people going with me this year. The coaches have explained it to me already. I told them I want to be there for the best. And this is their best. I'm excited for it. I'm excited to see all the fans. I've never seen Rupp. They say it's like 30,000 deep. I want to see that full. I want to see all the players, I want to see everything."
Johnson cut short the interview with reporters before discussing other schools, other than to say that Duke was "at the bottom of the barrel" because they weren't making him a priority.
Still, Johnson plans to take all five visits and then decide in the winter and sign in the spring.
"The official visits in the fall will mean a lot to me and...hopefully I'll make my decision by end of November, December, January and I'll sign in the late period," he said.