Rams vs. Cowboys exhibition at the Coliseum was more than two decades in the making

The Rams’ exhibition opener against the Dallas Cowboys on Saturday night will be the first NFL game played in the Coliseum in more than two decades. A crowd of nearly 90,000 could be on hand to be a part of it.

And while most Rams players and coaches are excited about the change of atmosphere after several seasons of sparse crowds in St. Louis, rookie quarterback Jared Goff remains characteristically low key about his NFL debut.

No big deal. It’s nothing to get overly excited about. He has played in hundreds of games.

“I can’t make it more than it is,� said Goff, the No. 1 pick in the draft. “I can’t blow it up in my head…. I don’t feel like I have any issue with the magnitude of it.�

Goff no doubt will be the focus when he emerges from the Coliseum tunnel onto the field, when he goes through warmups and probably after kickoff when he’s standing on the sideline.

That’s where the former California standout will spend the first few series, because Case Keenum is the Rams’ starter.

But Goff will take plenty of snaps.

The exhibition against the Cowboys is the first of four opportunities for Coach Jeff Fisher to evaluate Keenum and Goff and decide who will start the Sept. 12 opener against the San Francisco 49ers on “Monday Night Football.�

Keenum, a fifth-year pro, has taken nearly all of the first-team reps during training camp workouts and appears to have a consistent handle on coordinator Rob Boras’ offense.

But the Rams did not trade to the top of the draft to choose a backup quarterback.

Goff made numerous mistakes — expected from a young player — during rookie camp, off-season workouts and the first part of training camp.

As of late, he has more consistently displayed the arm strength, decision-making and footwork in the pocket that convinced Fisher and General Manager Les Snead that he was worth the draft gamble.

Last week, Goff performed well during a practice at the Coliseum. Now he gets his first test against an NFL defense other than the Rams’.

Rams rookie quarterback Jared Goff runs onto the field at the Coliseum before a scrimmage on Aug. 6.

(Gina Ferazzi / Los Angeles Times )

He is expected to play about two quarters.

“We want him just to relax,� Boras said, adding, “The more that he can go out there and just settle in, like we saw him settle in at the Coliseum during the [practice], he’s going to play confident.�

Goff did not receive a crash course on the Cowboys. Fisher said the Rams would do minimal game-planning for their exhibition opponent.

The focus, instead, is on evaluating players, especially those trying to make a roster that will be trimmed from 90 to 75 to 53 in the next month.

It remains to be seen how much work, if any, star players get Saturday night.

Running back Todd Gurley might carry the ball once or twice to please the fans, but Fisher is not expected to expose his most valuable offensive piece to injury.

The same goes for defensive tackle Aaron Donald, and players such as defensive end Robert Quinn, who is coming off back surgery.

But there are some job competitions worth monitoring.

Lamarcus Joyner, E.J. Gaines and Coty Sensabaugh are contending to start opposite Trumaine Johnson at cornerback. Gaines, who started 15 games in 2015, was sidelined for a few practices because of a hamstring issue but said he hoped to play Saturday.

Receivers Tavon Austin, Kenny Britt, Brian Quick and fourth-round pick Pharoh Cooper have roles, with sixth-round pick Michael Thomas, second-year pro Bradley Marquez and undrafted free agents Duke Williams and Nelson Spruce among those competing for a spot.

The most collective drama, in terms of competition for jobs, will come on kickoffs, field goals and punts as rookies attempt to increase their value.

“Everybody that’s covering a kick or returning a kick is trying to make the football team,� Fisher said.

The game will be a homecoming of sorts for Rams players who grew up or played college football in Southern California.

Former USC safety T.J. McDonald and former UCLA linebacker Akeem Ayers are among the players with local connections.

It has been more than 21 years since a crowd of NFL fans filled the Coliseum.

“Hopefully,� Fisher said, “we make some plays that they can be impressed about.�

Follow Gary Klein on Twitter @LATimesklein