Old reliable Case Keenum faces his old team, the Rams, as stand-in quarterback for the 7-2 Minnesota Vikings

Two months ago, this would have been the strangest sentence ever written:

The NFL game of the week is Jared Goff versus Case Keenum.

Thequarterbacks who were at the helm for last season’s 4-12 Rams fiasco are now directing two of the league’s hottest teams, with Goff’s 7-2 Rams playing at Keenum’s 7-2 Vikings on Sunday.

Whereas Goff, the No. 1 overall pick in 2016, is firmly entrenched as the future of the Rams, Keenum is playing on borrowed time. He’s keeping the spot warm for quarterback Teddy Bridgewater, who was activated for the first time last week after suffering a devastating knee injury on the eve of the 2016 season.

The Vikings haven’t announced which quarterback will start Sunday — why give the Rams extra time to prepare? — but they would be crazy to bench Keenum now, considering he’s been an integral factor in their five-game winning streak. He threw four touchdown passes in a 38-30 victory at Washington on Sunday, a performance so impressive that it wasn’t even dampened by his two interceptions at the end.

Goff has been outstanding all season, silencing those critics who had hastily written him off as a bust when the Rams went 0-7 with him as the starter in the second half of his rookie year. Los Angeles leads the league in scoring at 32.9 points a game — the precise average of the 1999 “Greatest Show on Turf” St. Louis Rams — and in the past two weeks Goff has seven touchdowns and no interceptions.

“Talent-wise, I think Jared’s top tier in the league,” Keenum said last week, sitting with a reporter in an equipment room at Vikings headquarters. “He’s very talented. He’s got some talented guys around him.”

Keenum, the son of a football coach, is careful and diplomatic in choosing his words. He doesn’t want to delve into the details of Goff’s improved offensive line, which has gone from the league’s worst to one of its best; the resurgence of Todd Gurley, who finally has some running lanes; the suddenly sure-handed cast of receivers, and, most important, the coaching upgrade from Jeff Fisher to Sean McVay.

Keenum said he harbors no ill will about the Rams letting him walk, a foregone conclusion when they gave up so much to move up to draft Goff.

“I could sit here and go through all the excuses and have a pity party for myself, ‘This is bad that happened to me. This is out of my control,’ ” Keenum said. “But I don’t see it that way. I see that I’ve made [31] starts in the NFL now. I’ve had a lot of fun.”

Never more fun than now, when Keenum is finally surrounded by an all-around good team. Yardage-wise, the Vikings are fifth in defense and ninth in offense. They have won five in a row, a feat surpassed only by the 8-1 Philadelphia Eagles and 7-2 New Orleans Saints, whose winning streaks have reached seven.

Keenum, promoted to the starting lineup in Week 2 after Sam Bradford was sidelined with a bum knee, has far exceeded the expectations of most observers. He has 11 touchdowns, five interceptions, has been sacked only five times, and has a career-high passer rating of 92.6.

Although he was not drafted out of Houston, and in six NFL seasons has bounced from the Texans to the Rams to the Vikings, Keenum does not have the mentality of a backup. He’s not a play-it-safe dink and dunker. He boldly tries to squeeze passes into tight windows, which sometimes gets him in trouble. But he clearly has confidence.

“Case has been a winner his whole life,” receiver Jarius Wright said. “Some people don’t realize, that plays a big part in winning and losing. You put a guy in there who knows how to win, and that’s hard to coach that to people.”

So what went wrong with last year’s Rams?

“That’s the million-dollar question, more than a million, really,” Keenum said. “There’s a lot of things that go into winning a football game.

“It’s tough when you see momentum going against you like we had. It’s a tough league and nobody’s going to let up. It’s sharks smelling blood in the water. They were pouncing.”

And this year’s stunning turnaround?

“I’ve been around long enough to know that you’re never surprised with anything,” he said. “Any week in this league there are so many things that can happen. Decisions made. Teams that should win, don’t. Teams that shouldn’t win wind up winning.

“[The Rams] are putting up a lot of points. I’ve only watched one or two of their games on film, but Jared is doing a good job. He’s getting the ball out and giving his guys chances down the field, and they’re making plays for him.”

Keenum is careful to say he doesn’t aim to prove the critics wrong about him, but to prove correct the people who believed in him. Still, he couldn’t suppress a smile at the thought of facing his old team.

“When I saw that we were playing the Rams, you definitely have that one circled,” he said.

Former NFL quarterback Rich Gannon understands. He’s the patron saint of backup quarterbacks, having played well enough as a No. 2 in Minnesota, Washington and Kansas City to earn the starting job at various points, yet never getting the chance to have a team he could truly call his own.

That’s until he got to Oakland and was handed the keys to the Raiders by a young Jon Gruden. In the final game of the 1999 season, Gannon took the Raiders back to Kansas City and beat the Chiefs in overtime 41-38, a victory that likely saved the job of the embattled Gruden.

So Gannon — who later in his career went on to become the NFL’s most valuable player and lead Oakland to a Super Bowl — has a good idea of what Keenum must be feeling in facing the Rams.

“I wanted to stick it to the Chiefs so bad; I liked a lot of those guys, but I just wanted to send a message to the organization,” Gannon said. “But playing against your former team, you’ve got to be able to control your emotions. I’ve seen a lot of guys get so worked up that they go out and just play like garbage.”

The Rams still are very fond of Keenum. For instance, at a charity auction last year, general manager Les Snead bid for and wound up buying a game-worn Keenum jersey from the team’s victory over Arizona.

“Kara asked me if we should give it to Case, and I said, ‘No, I’m keeping this one for us,’ ” Snead said, referring to his wife.

Snead is not the sentimental type. The couple has moved six times in three years, parting ways with Kara’s piano in one move, and their only TV in another. But he keeps that Keenum jersey, which hangs in his closet right next to his own jersey from his playing days at Auburn.

“The thing about Case is, if you don’t think he deserves the job, he’s kind of proving you wrong every week,” Snead said. “He’s earning it.”

sam.farmer@latimes.com

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