Early in August, Case Keenum arrived at Bills training camp disguised as a fan. Wearing a bucket hat and glasses, Keenum tricked several of his teammates into signing autographs on a football before realizing they had been duped by their new second-string quarterback.

Keenum joked at the time that “no one knows” who he is, because he was the faceless backup to Josh Allen. But he might have to shed his disguise once and for all this week if he’s forced to take over for Allen as the starter.

Allen is nursing a sore right elbow, which he injured on a strip sack late in Sunday’s loss at the Jets. Head coach Sean McDermott declared Allen “day to day” on Wednesday and, not surprisingly, wouldn’t say whether he would be able to play on Sunday against the Vikings.

But considering the cautious nature of the Bills on player injuries, and the need to make certain Allen doesn’t aggravate the elbow, there’s a strong likelihood that Keenum will be taking starters’ snaps on Sunday at Highmark Stadium.

This, of course, is why the Bills traded for the 34-year-old Keenum in March. They saw him as a perfect backup for Allen, a seasoned veteran who has been in high-pressure situations and would be able to keep an elite offense functioning at a high level in an emergency.

Keenum, no stranger to these situations, sounded ready when he met with the Buffalo media in front of his locker after Wednesday afternoon’s practice.

“I feel great,” he said. “I’m doing the same thing I do every week. I prepare to play every week, every day, every period, every practice, every meeting. So, it’s the same. Just got a few more reps today.”

On Sunday, he might take over an offense still reeling from that stunning loss to the Jets, one that has struggled mightily over the last six quarters. Oh, and Keenum could be going up against a Vikings team for which he enjoyed his greatest triumph as a pro in 2017.

Keenum was asked if he was a little more wired to face Minnesota. He went 11-3 as a starter for the Vikings in 2017 and got them to within a game of the Super Bowl — after winning a divisional round game on the famous “Minneapolis Miracle”, a 61-yard touchdown pass on the final play of the game to his current teammate, Stefon Diggs.

“Yes and no,” he said with a chuckle. “I’ve played a lot of my former teams before. That’s what happens when you have a lot of former teams.”

Keenum has been the ultimate journeyman. The Bills are his eighth team in 10 years. At one point, he played on seven teams in seven years. OK, a list: Houston, St. Louis, LA Rams, Minnesota, Denver (where he got a big free agent deal after ’17), Washington, Cleveland.

He played the last two seasons as Baker Mayfield’s backup with the Browns. Keenum started two games a year ago. Cleveland won them both at home — 17-14 over the Broncos in October and 21-16 over the Bengals in the season finale.

That’s a formula the Bills will settle for if Allen has to sit a game or two. Win with strong defense and efficient, mistake-free quarterback play (Keenum completed 67 percent of his passes for 375 yards with three TDs and only one interception in those two games).

McDermott, who resisted all attempts to elaborate on Allen’s injury, seemed confident in his team’s offense’s ability to perform at a high level without his superstar QB.

“This is not Case’s first day with us,” McDermott said. “Nor is this process new to Case in terms of his role or potential role. So he’s been through this before. We have full confidence in Case and Matt Barkley, and we shape a game plan accordingly based on what we know right now.”

Diggs was a third-year pro when Keenum took over for the Vikings in 2017 after Sam Bradford went down with a knee injury. He knows how he responds to a crisis.

“I have complete confidence in him,” said Diggs, who is tied for third in the NFL in catches with 60. “I’ve seen him in action. I remember clear as day a time when we had a quarterback go down and Case Keenum had to play.

“He’s a winner,” Diggs said. “He’s a dog. Case is a professional and all those good things. But when he gets out there, he’s competing at a high level and he gives you the confidence that you can win, whether it’s with his arm or him improvising and making things happen.”

Keenum said after half a season of work as the backup, he’s on the same page with the Bills’ receivers, and he’s happy to get a starter’s reps in practice.

“But honestly, I get all those reps because I stand right behind Josh and I watch where he’s throwing the ball,” he said, “and those guys’ body language coming in and out of breaks.

“I’ve gotten a lot of those reps with my eyes, the feel and visualization, so I’ve done a lot of those before and it’s just a matter of putting them into place.”

Keenum said the Bills’ offense can be “whatever we want it to be.” He went out of his way to praise the offensive line, the running backs, the wide receivers and tight ends, the coaches, everyone but the office staff.

The Bills do lead the NFL in offensive yards per game, and they’re third in the league in points per game behind the Chiefs and Eagles. But there’s been a lot of discussion on radio and social media about the lack of production by the receivers outside Diggs.

Diggs has 60 catches. No other wideout has more than 20 this season. Gabe Davis, Isaiah McKenzie and tight end Dawson Knox have 58 receptions combined.

Buffalo Bills quarterback Case Keenum (18) throws the ball during an NFL football game against the Tennessee Titans, Monday, Sept. 19, 2022, in Orchard Park, N.Y. (AP Photo/Kirk Irwin)

“I haven’t heard any of that around here,” Keenum said. “We really don’t listen to much of that.”

Well, your own head coach admitted that you need to spread the ball around more in the passing game and develop the offense a little more, I told him.

“We all want to produce,” Keenum said. “I want to produce. I’ve been on the sidelines. I think everybody loves the game and wants to do well. Whoever gets in the end zone, it doesn’t matter who’s the one, we’ll all meet him and celebrate when we get there.”

That will make for the usual delirious scene inside Highmark Stadium, where the Bills are 3-0 this season and have won seven games in a row, including the playoff rout of the Patriots, and averaged 34.3 points in those seven victories.

Keenum was enthusiastic about the chance to perform in front of Bills Mafia and get a win against a Vikings team that will come to town on a six-game winning streak.

“I came in for some mop-up duty early in the year,” he said. “In the fourth quarter we were up by 40 (it was actually 34 over the Titans) and everybody was still on their feet the entire game.

“I imagine if I do get to play early, it’ll be pretty special,” Keenum said. I’ll have to calm myself down a little bit. It’s pretty electric over there.”

Win Sunday and he’ll have no chance of hiding his face in this town. Keenum won’t be the one asking for autographs, he’ll be the guy signing them.