ATLANTA – Joshua Dobbs didn’t know how to address many of his teammates. “I knew a lot of first names, and nicknames,” he said.

In his first four days with the Vikings, he had not taken a snap with the first-team offense.

Dobbs spent the latter part of the week cramming for his first test as a backup quarterback to Jaren Hall against the Falcons in Atlanta. On his first drive after Hall left the game because of a concussion, Dobbs was sacked for a safety. On his second drive, he lost the first of his three fumbles on the day.

If ever a quarterback was set up for failure, it was Dobbs on Sunday. He was playing a formidable defense in a noisy stadium while his new head coach shouted strange instructions into the speaker in his helmet as he ran an offense that, by the end of the game, was lacking its star receiver, star left tackle, third receiver, backup running back, franchise quarterback and backup quarterback.

With a 6-yard touchdown pass to reserve receiver Brandon Powell with 22 seconds remaining, Dobbs culminated a series of comebacks to earn a 31-28 victory over the Falcons at Mercedes-Benz Stadium, “The guy learned the playbook in three days,” said guard Dalton Risner, signed by the Vikings Sept. 19. “Took me three weeks.”

Dobbs, a student of aerospace engineering at Tennessee, grew up in nearby Alpharetta, Ga. Tuesday, the Vikings traded for him, and he left Arizona for Minnesota. Saturday, he flew to Atlanta with the team and dined with his parents. Sunday, he led the Vikings back from deficits of 11-3, 14-10, 21-13 and 28-24.

“Learn as you go, hair on fire, hang onto your seat,” Dobbs said with a smile.

He completed 20 of 30 passes for 158 yards and two touchdowns without an interception. He rushed seven times for 66 yards, displaying that his feet can be as quick as his synapses.

Backup quarterbacks don’t practice with the first team, and Dobbs wasn’t an ordinary backup. He was, in a way, the Vikings’ fourth quarterback, behind injured starter Kirk Cousins, injured backup Nick Mullens and the rookie Hall.

After his mistakes helped the Falcons to the lead, Dobbs threw for two touchdowns and a two-point conversion and ran for another touchdown over the final 31 minutes of the game, lifting the spirits and playoff odds of a team that, a week earlier, spent much of the postgame staring into the distance and crying after Cousins was lost for the season because of an Achilles tendon injury.

Dobbs followed Vikings coach Kevin O’Connell to the postgame interview room and began with: “What’s up, y’all. Josh Dobbs. Honored to be in Minnesota and to introduce myself.”

The Steelers chose Dobbs in the fourth round of the 2017 draft. He is with his seventh NFL team. The Cardinals were prepared to bench him before trading him to the Vikings in a deal that included a swap of low-round draft picks.

His game-winning throw went from one journeyman to another — Vikings punt returner and reserve receiver Brandon Powell, who is with his sixth team since joining the league as an undrafted free agent out of Florida in 2018.

The two had never so much as played catch before Sunday morning, although Dobbs knew his name from their time together in the SEC.

By late Sunday afternoon, Dobbs had learned that the best way to learn names in the NFL is via end zone and locker room celebrations.

“It’s like if you were taking Spanish all year,” Dobbs said, explaining the process of learning a new offense. “You showed up on Wednesday and someone told you you’re taking AP Spanish, and someone told you you have an AP French exam on Sunday. Someone’s going to speak to you in Spanish and you’re going to have to translate it into French.”

In the final seconds, O’Connell wrapped his arms around Dobbs on the sideline. If this had been a movie, he would have been saying that this may be the beginning of a beautiful friendship.