ASHBURN, Va. -- Washington Redskins rookie Dwayne Haskins will make his first start Sunday against the Buffalo Bills, but whether or not this is a permanent role remains to be seen.

Interim coach Bill Callahan said Haskins will start because Case Keenum remains in the concussion protocol. Colt McCoy will be the backup Sunday against the Bills (5-2), who have the NFL's third-ranked pass defense.

Haskins, the 15th overall pick in the draft, has made two relief appearances this season -- the Redskins trailed by at least a touchdown in both outings when he entered. For the season, Haskins has completed 12 of 22 passes for 140 yards and four interceptions with no touchdowns.

Callahan said there was no guarantee Haskins would start beyond Sunday.

"We're just looking at one game," Callahan said.

Three other rookies already have started multiple games this season -- Kyler Murray (Cardinals), Daniel Jones (Giants) and Gardner Minshew (Jaguars). Ryan Finley (Bengals) also is starting this weekend.

Haskins was the last of the three quarterbacks drafted in the first round to play.

The Redskins had wanted Haskins to sit as long as possible this season, knowing he had started only 14 games at Ohio State. That inexperience for a pocket passer could be seen and felt in numerous ways: calling plays in the huddle, pre- and post-snap reads of the defense and the tempo.

The Redskins hope Haskins will be helped in those areas by getting the majority of first-team reps in practice this week -- the most practice reps he's had all season. Haskins declined comment Friday, saying he wanted to wait until after the game to address the start.

"We've seen him progress throughout the week," Callahan said. "That's the big thing. His improvement day to day from situation to situation, from drill to drill, you see nothing but a locked-in focus. He had a pretty good early start of the week and finalized today with a lot of red zone work. We're very encouraged."

Even when Haskins wasn't the starter this season, the Redskins always had a package of plays ready for him just in case. That's what they used when he entered a Week 4 loss to the Giants as well as last week's loss to the Minnesota Vikings.

That led to leaked stories about various aspects of his readiness, including how well he knew the plays.

"I wouldn't say he didn't know the plays," said Redskins receiver Terry McLaurin, who played with Haskins at Ohio State. "It's different hearing it in the ear piece and then calling it because there's so many things going on. That comes with reps; that comes with the visualization; it comes with preparation.

"His reads have been really clean this week. He knows what he's looking at. If it's one-high, two-high [safeties], he knows which side he's working the route combination. He's been really clear the way he's calling the plays."

McLaurin called Haskins "very businesslike, very serious" this week.

"He's been working on his command in the huddle," McLaurin said. "I feel that is very important because that permeates throughout the whole offense, gives the line confidence, gives everybody confidence that you know the call, you know what you're looking at and you can go out and execute. That's very big for him. I feel I've seen that jump, the biggest jump since he's been playing this year."

McLaurin, a captain and leader at Ohio State, worked with Haskins throughout the summer on calling plays. But he's also working on Haskins' mentality.

By all accounts, Haskins has been energized since coach Jay Gruden was fired. It was oft-reported that Gruden did not want to draft Haskins in April.

Said Haskins on Wednesday: "It's just a change in me. A lot of stuff."

"You want to keep his confidence high," McLaurin said. "He lives and dies off every rep, every play, every situation. And I told him, 'It's great to have that emotion, but at the same time you want to have that next-play mentality. Things are going to go well in a game; things are going to go bad. You're the quarterback. You've got to have a poker face.'

"He hasn't been perfect this week, but he's really improved the way he's executed and calling the plays and the way he's prepared."