FRISCO, Texas -- On Aug. 13, 2016, when Dak Prescott walked into the Los Angeles Coliseum for the first time, he was already envisioning what's coming on Saturday.

Prescott was a fourth-round pick then, trying to show the Dallas Cowboys he could be Tony Romo’s backup, but the big picture was always on his mind. He was confident he would be a starting quarterback in the NFL. He was confident he would be in a position to take a team to a playoff game, as he will Saturday (8:15 p.m. ET, Fox) against the Los Angeles Rams.

It wasn’t something he dreamed; it was something be believed.

“I guess I couldn’t imagine it being back in the Coliseum against the team I started off my career,” Prescott said, “but I’ve always talked about the confidence I’ve had in myself and this team. Nothing has changed.”

The Coliseum was abuzz on that warm August day. It was the Rams’ first game back in Los Angeles. The stadium was full of fans and the game was nationally televised, with ESPN’s Monday Night Football crew calling the action.

Prescott was starting because Kellen Moore, who is now the Cowboys quarterbacks coach, had suffered a broken ankle 10 days earlier and, as a veteran, Tony Romo was not going to play in the first preseason game.

Jason Witten didn’t play, but Dez Bryant and Terrance Williams did. Tyron Smith didn’t play, but Travis Frederick and Zack Martin did. Ezekiel Elliott was kept out because of a hamstring strain, but three-time 1,000-yard runner Alfred Morris played.

“We were playing that game with the idea that we wanted to see what we had,” offensive coordinator Scott Linehan said. “It really was probably everybody’s first glimpse of what Dak’s about.”

Prescott had only a couple of practices with the first-team offense during training camp in Oxnard, California, with Romo resting every third day. He did not take first-team snaps during organized team activities and the minicamp in the spring. Back then, the Cowboys just wanted him to get better at taking a snap from center.

When he joined the first-team huddle in camp, a future Hall of Fame tight end (Witten), three All-Pro offensive linemen (Smith, Frederick and Martin) and the franchise’s all-time leader in touchdown catches (Bryant) were staring at him.

“Immediately off the bat, you could tell he was born to be a leader,” Frederick said. “And knew exactly what he was doing and what he wanted to be doing. He never struggled with calling the plays or you never saw him feel like the game was too big for him, even when you looked around the huddle and saw those guys that were there.”

So maybe it was not surprising to many that Prescott flourished against the Rams. He completed 10 of 12 passes in the first half for 139 yards and had touchdown throws of 10 yards to Bryant and 32 yards to Williams. He had a 14-yard run, too, and completely outperformed the No. 1 pick of the 2016 draft and his counterpart Saturday, Jared Goff.

After Moore’s injury, the Cowboys had considered trading for Josh McCown and had talks with free agent Nick Foles to be Romo’s backup. Prescott’s performance ended those discussions.

“At the end of the day, it was so much better than we thought it would be,” executive vice president Stephen Jones said.

Twelve days after his debut against the Rams, Prescott became the Cowboys starting quarterback when Romo suffered a compression fracture in his back.

Prescott has started every game since, winning 33 games, including his first postseason game against the Seattle Seahawks last Saturday in the wild-card round. He has a Rookie of the Year award on his résumé as well as a Pro Bowl appearance.

“I’m not saying I always knew he was going to be where he is now,” Linehan said, “but I think we all had a gut feeling that he was going to be a hell of a player in this league.”

Now he has the Cowboys in position to advance to their first NFC Championship Game since 1995.

When he walks out on to the Coliseum turf on Saturday, his mindset will not be too different from the one he had when he took the field on Aug. 13, 2016.

“I don’t ever just go out to play the game,” Prescott said. “When I go out, I go out to play the game, I go out with the mindset to win, like I’m the No. 1, like I’m the guy whether I was then or not. It’s just kind of the way I have to approach it all. It all worked out.”