The Redskins (6-7) have lost four in a row as injuries have ravaged the team, especially at the quarterback position. Alex Smith and Colt McCoy suffered season-ending injuries, and Mark Sanchez was ineffective, so Johnson will become the fourth quarterback to start a game this season for the Redskins, who desperately need a win to stay in contention for a playoff berth.
Johnson performed well in relief of Sanchez last week, completing 11 of 16 passes for 195 yards and a touchdown and running for an additional 45 yards in the 40-16 loss to the New York Giants.
He was signed by the Redskins last week, and has been on the roster of 12 different NFL teams. But he has some familiarity with Redskins head coach Jay Gruden. Johnson, 32, was with Gruden in Cincinnati in 2013 when Gruden was the offensive coordinator there.
"Ironically, Jay yelled at me enough out there to where it kind of stuck in my head on certain things on how he wants things done," Johnson said. "Stepping back in here has kind of eased my way through the little things a little bit better. There are some things that have changed, but again my journey has put me in so many different systems I've learned a huge amount of football from a lot of great football minds."
With just a few days of practice under his belt, Johnson will start in a critical game for the Redskins, who probably need to win their final three games just to have a chance for a playoff berth.
"Josh played with or against everybody in the league, so for starters he knows everybody on the Jacksonville defense," Gruden said. "The big reason we wanted him is because of his familiarity with what we do. Being at Tampa (Bay), there's some carryover and obviously being at Cincinnati for the length of time that he's with us there's a lot of carryover that he remembers and can handle. Now it's a matter of honing in on his skillset and trying to come up with a plan to utilize his strengths."
Johnson will be without at least one prime receiving target and possibly two. Tight end Jordan Reed, who leads the team in receptions (54) and receiving yards (558) might miss the rest of the season with a toe injury, and wide receiver Josh Doctson, who is second in receptions (39) and receiving yards (469), has been unable to practice this week as he goes through concussion protocol.
Johnson will be tested by a Jaguars defense that ranks sixth in the NFL in total defense and eighth in scoring defense, yielding 21.0 points per game.
But the Jaguars (4-9) have lost seven of their last eight games to fall out of playoff contention one year after reaching the AFC Championship Game.
The Jaguars thought their defense was back when they shut out the Colts in a 6-0 victory that ended a seven-game losing streak two weeks ago. But the next Thursday night, they were shredded by the Tennessee Titans 30-9 as Derrick Henry ran for a Titans record 238 yards and four touchdowns.
Redskins running back Adrian Peterson is coming off a game in which he had just 16 rushing yards on 10 carries, but he is still a threat if the Jaguars tackle as poorly as they did against Tennessee.
"We are going to put a lot of emphasis on tackling," Jaguars head coach Doug Marrone said this week. "You have a running back coming in here, Adrian Peterson, that has those qualities. Tough to bring down. Gets a lot of yards after contact and things of that nature. That is a challenge. We understand that. We can't tackle like we did last week against this team."
Kessler will make his third straight start Sunday as the Jaguars try to give a good showing in their final home game of the season.
"I have talked to (the players) about that," Marrone said. "It has been disappointing and we understand that. This is our last time to play at home. Let's go out and give a good performance. We owe it to the fans. They have been through (this season) just like we have been through this season.
"For us, it is extremely important to go out there and play well and get a win."
The Jaguars will lean heavily on running back Leonard Fournette, who has played only six games this season and was limited to 36 yards on 14 carries in the loss to Tennessee.
Fournette has just 350 yards this season after rushing for 1,040 yards a year ago.