Johnson is out for personal reasons, while Garnett is getting a rest day.
Garnett played the entire fourth quarter of Wednesday night's 113-107 loss to the Washington Wizards, and the Nets want to conserve the 37-year-old veteran so he's healthy throughout the 82-game regular season.
Small forward Paul Pierce will start in Johnson's place after coming off the bench for the previous five games since returning from a broken bone in his right hand. Pierce had a season-high 27 points Wednesday night. Mirza Teletovic will start in Garnett's place.
Garnett, 37, is shooting 37.9 percent from the field and has averaged 6.5 points and 7.2 rebounds in 22.1 minutes per game. He played 25 minutes in Wednesday night's 113-107 loss to the Washington Wizards -- including the entire fourth quarter.
Garnett has played in 23 of the team's 25 games. He also sat out Nov. 29 in Houston. Brooklyn's next game is Monday against the Indiana Pacers.
"He's a competitor. He wants to compete. He wants to help this team win," Nets coach Jason Kidd said of Garnett. "But I think he understands why I'm giving him the rest day with all the time he spent on the court in that last game, I felt he deserved to have some time off."
Statistically, the Nets (9-16) are 5.9 points per 100 possessions better offensively without Garnett on the court as opposed to with him (105.0 to 99.1). Defensively, though, they are 2.4 points per 100 possessions worse (104.9 to 107.3) without him.
Johnson had a career-high 10 3-pointers and a season-high 37 points in Monday night's 130-94 victory over the Sixers.
"Every day is just a step forward; there haven't been any steps back," Terry said. "I couldn't run Monday; Tuesday I was running. Wednesday I was running through the plays; today a similar-type deal. Tonight, probably more moving and cutting. Hopefully [he'll play] next week."
The Sixers' Michael Carter-Williams (skin infection, right knee soreness) will start. The rookie point guard has missed the past eight games, and his team has lost all of them.
"They're a different team with him in there," Nets point guard Deron Williams said. "Their tempo changes, their pace changes. He's a great young point guard trying to make a name for himself. It's gonna be a good matchup."
Williams said he didn't have his legs Wednesday but said he feels better and is ready to go.
"We've been dealing with [injury] stuff all year, guys being in and out of the lineup, so if we're not kind of used to it by now, it's sad," Williams said. "But we definitely will miss KG out there, his energy, his intensity. And also if Joe can't go, we're missing a lot of scoring. All the guys are gonna have to step up -- myself included -- and try to find a way to get a win."