The CFL's top defensive player in 2011 will switch from cornerback to safety when Winnipeg (2-9) hosts the Edmonton Eskimos (2-9) on Friday night.
Injuries are also forcing two new offensive linemen who began practising Tuesday to make their CFL debuts in the battle between the league's two worst teams.
Edmonton snapped an eight-game losing streak last weekend with a 25-7 home win over the Bombers.
"I've been in the defence probably longer than all of our coaches so I know what's going on, I know the defence inside and out," Johnson said after Thursday's walkthrough. "It makes more sense to move me to safety and switch one guy versus moving three guys that are all rookies into different spots and having them learn new jobs on the fly."
Johnson, who hasn't played safety since November 2011, replaces the injured Cauchy Muamba (ankle). Defensive back Marty Markett will move to Johnson's corner spot.
Edmonton head coach Kavis Reed predicted Johnson will do just fine with his new role.
"Jovon is a very cerebral football player," Reed said. "I know he'll be able to make all the checks.
"He's more explosive than people think and he's very instinctive. And those are a lot of the qualities of a free safety."
After injuries to veteran offensive tackles Glenn January and Shannon Boatman, the Bombers brought in Americans Dan Knapp and Jarvis Jones and they'll see action at right and left tackle, respectively.
"It's strange but I'm actually excited about it," said Knapp, who played in four NFL exhibition games last year with the Oakland Raiders.
The biggest differences Knapp must adjust to are the new rules and defences lining up a yard off the ball.
"It's something I've got to adjust to, but I've been playing this game since the sixth grade," he said. "It comes natural, to a certain extent."
Edmonton defensive ends Marcus Howard and Odell Willis will try to take advantage of the newcomers.
"Hopefully I can and hopefully I do because if I don't the guys will get on me," Howard said.
Howard noted he joined the Eskimos three years ago on a Wednesday and got into the lineup two days later because of an injury to current Bomber Greg Peach.
Willis said there may be a few CFL "tricks" they can throw at Knapp and Jones, but he doesn't expect the newcomers to be too out of sync.
"Even though they're two new tackles, I don't think this will be their first time playing football," Willis said.
Knapp and Jones will have the task of helping protect starter Max Hall, another change from last week's roster.
For those trying to keep track of Winnipeg's quarterback carousel, former Bomber Buck Pierce (traded to B.C. on Sept. 8 for receiver Akeem Foster) started the club's first four games before being injured. Justin Goltz then started two games, Hall the two after that before Goltz returned to start the last three contests.
The six-foot-four Foster will also play his first game for the Bombers, replacing injured receiver Cory Watson.
Bombers head coach Tim Burke said Hall was projected to be the No. 1 quarterback prior to being injured in Winnipeg's 37-14 road loss to Hamilton, just two plays into his second career start. But then, Goltz did relatively well in relief.
Since Hall replaced a struggling Goltz in last weekend's game and showed flashes of being able to move the offence, Burke wants to see if he can do so for the remainder of the season.
"I hope so," Burke said. "That would be great."
He added Jason Boltus will back up Hall ahead of Goltz.
Winnipeg is last in the CFL in scoring (224 points), first downs (174) and passing (2,237 yards), second-last in fumbles (20) and fifth in rushing (1,029 yards).
Having newcomers Knapp and Jones on the line isn't a big concern for Hall.
"Physically, they're both good players," Hall said. "They're very capable guys.
"I'll trust they'll play well. I have to. I can't worry about it. I can't look at the rush. I have to go through my reads and trust those guys will do it."
Edmonton's offence is tied with Montreal for second-last in scoring (259 points), ranked sixth in first downs (204), third in rushing (1,162 yards) and has a league-low 12 fumbles.
The Eskimos' roster remains basically intact since last week and the offence will again be spearheaded by quarterback Mike Reilly. Reilly was named the CFL's offensive player of the week after completing 16-of-25 passes for 196 yards and three touchdowns while rushing nine times for a career-high 113 yards versus Winnipeg.
Reilly's 530 rushing yards are tops among CFL quarterback and fifth overall.
"It's something that's worked to this point and anytime it's available we're going to use it," Reilly said. "But I don't think it's something you want to use at the expense of taking away your pass plays."
NOTES: Winnipeg hasn't thrown a touchdown pass in its last four games and has just five this season . . . Edmonton's Fred Stamps is the CFL's leading receiver with 44 catches for 821 yards and nine TDs. A 10th touchdown grab would be his career-best . . . Winnipeg has trailed by 20 or more points in six of its last eight games . . . The Bombers will be trying for their 600th all-time win (in game No. 1,164). Edmonton is the only CFL club to have more than 600 wins.