– A self-professed thin man his whole life, Timberwolves forward Chris Johnson has shown up for Las Vegas Summer League play with at least 15 pounds of new muscle added on his skinny frame and a contract guaranteed in full for next season.

He’s adjusting to each for the first time.

“I’ve been skinny my whole life,” he said. “I’m just trying to get used to this extra weight.”

Now at 6-11 and a whopping 230 pounds, Johnson is also adjusting to the knowledge he has $916,000 due him for this coming season after he knocked around Turkey, Poland, the NBA Development League and with three other NBA teams in the four years since he left Louisiana State.

At age 28, he now has a steady job, or at least a guaranteed payday after Wolves boss David Kahn signed the former 10-day contract signee without announcement for 2013-14 near the end of last season.

“It was quiet,” Johnson said of one of Kahn’s last official acts before he was replaced by Flip Saunders in early May. “It takes the pressure off a little bit. I can just focus on playing.”

He is focused on trying to apply that new muscle and on Monday he did as the Wolves’ starting center against a Phoenix team that started — and rode down the stretch — brothers and former lottery picks Marcus and Markieff Morris up front in the Suns’ last-second 91-89 comeback victory.

Johnson played 20½ minutes, scored three points, had seven rebounds, two blocks, three assists and six personal fouls but didn’t foul out because in summer-league you get 10.

The Suns won on Marcus Morris’ buzzer-beating shot after they trailed by 24 points on a day when Wolves summer league coach David Adelman said of the opposition, “They’ve got NBA guys and they made NBA plays in the fourth quarter.”

Johnson faced two of those NBA guys Monday, matchups to which he must adjust because he’s now one of them, too.

“They had some men out there,” Adelman said. “I thought Chris actually handled himself pretty well on the boards. It was hard because he had six fouls and I only remember two. That was tough for him. Every time he moved, they called a foul.”

Johnson, who celebrates his 28th birthday on Wednesday, played his second summer-league game with that new upper body changed by working out at Nike’s campus in Portland, Ore.

He’s getting used to those new muscles and Adelman is getting used to seeing them.

“You can see it, especially in his chest and his arms,” Adelman said. “He looks better and he needs it. I know it’s tough to put on weight with guys like that, so it shows you he’s been working on it. Chris is light in his legs, so he’s going to have issues with that. But there are also positives: He’s really springy.

“So there’s going to be issues with that, but he’s got to something on top no matter what, more so for the wear and tear of an NBA season.”

Many Timberwolves fans last season were smitten with Johnson’s bounce and shot-blocking abilities on a team that lacked such a talent. Signed along with Mickael Gelabale to two 10-day contracts in January before he was kept for the rest of the season, Johnson now will compete against first-round pick Gorgui Dieng, whom the Wolves selected 21st overall in last month’s draft partly because he has that same skill.

At that $916,000 salary Johnson is about as expendable as an NBA player gets should the Wolves decide they need an extra roster spot come October. So while he’s guaranteed that money, he knows he’s not necessarily guaranteed a job come opening night.

“Just continue to keep proving to the coaching staff that I belong here,” he said, referring to his summer and fall goals. “The main thing for me is defense. I felt like I was a little bit of a liability against bigger guys, Al Jefferson and guys like that. That limited me some for playing time. That’s why I wanted to get bigger, stronger. That’s why I did.”