EAST RUTHERFORD, N.J. — The initial tests on rookie cornerback Deandre Baker‘s knee left some doubt. He felt something at practice on Sunday and an MRI left open the possibility it could be serious.

This would have been devastating for the New York Giants, who are banking heavily on the first-round pick. Baker has looked like he belongs from the second he arrived as the 30th overall pick out of Georgia. He’s expected to start at cornerback opposite Janoris Jenkins, and has been working with the first-team defense since the spring.

The news that it was a knee strain, and further tests that came back showing minimal damage, allowed the Giants to exhale. Baker is listed as day-to-day. There is hope he’ll be back within weeks and he “definitely” expects to be ready for Week 1.

It would be a huge win for their defense.

“It’s a big relief, certainly,” coach Pat Shurmur said this week after receiving the promising news.

Baker was the third of three first-round picks for the Giants, but he has a good chance to have the biggest impact this season. Daniel Jones warrants the most attention because he’s a quarterback and was selected sixth overall, but he’s expected to spend a large chunk — or the entire season in John Mara’s ideal world — as Eli Manning‘s backup. Dexter Lawrence (pick No. 17) isn’t likely to be an every-down player at 340-plus pounds.

Baker might never come off the field, barring injury.

There is a reason. He didn’t allow a touchdown last season at Georgia and won the Jim Thorpe Award, given to the top defensive back in college football. He has stood out to players and coaches throughout the offseason.

“The way he moves, the way he physically competes. You can’t really fake that,” veteran safety Michael Thomas said. “The questions he would answer in meetings — I sit next to him in meetings — I know he knows football.

“OK, then we get out [on the field]. The way he moves. The way he breaks. The way he can assess routes and concepts and stuff like that. So this guy can play. And to see him compete, he wasn’t scared to challenge any of the No. 1 receivers.”

Thomas raved about the way Baker takes notes and consumes football. He also hasn’t seen Baker back down against the likes of Sterling Shepard or Golden Tate. Baker played well in his first preseason game, aside from a pass interference penalty when he unnecessarily grabbed despite good coverage.

There is no backing down by the rookie cornerback. Veteran safety Antoine Bethea attributed it to Baker’s Miami-style swag. The I’ll-go-up-against-anybody-at-any-time attitude.

“Just go out there and compete, that’s all I try to do,” Baker, a Miami native, said of the approach.

The confidence exuded in so few words from the soft-spoken Baker can be construed as the cockiness necessary to be a successful cornerback. That’s part of what has the Giants believing he can be good early in his career at one of the game’s most difficult positions.

And they need it. They’re counting on some of their young cornerbacks to have immediate success, with Baker at the top of the list.

On-the-job training

Bethea likens this year’s Giants secondary to that of the 2009 Colts. That team had rookie cornerbacks Jacob Lacey and Jerraud Powers start a combined 21 games in the regular season on the way to the Super Bowl.

This Giants team is looking at Baker, Julian Love and Corey Ballentine — all rookies — to potentially contribute this season. The Giants are also hoping to get something from last year’s third-round supplemental pick, Sam Beal, who missed all of 2018 with a shoulder injury and most of this summer with a hamstring problem.

Second-year nickelback Grant Haley just returned from a shoulder injury and is working with the starters. Beal remains sidelined and Baker is out at least a few more days. Ballentine, this year’s sixth-round pick, has taken some first-team reps. So has Antonio Hamilton.

The Giants’ biggest bet is on safety Jabrill Peppers, the one player who seems stuck in that middle ground between seasoned vet and raw youngster. He’s expected to be their No. 1 playmaker in his third professional season.

It’s essentially Bethea, Thomas and Jenkins serving as the room’s veteran core. They’re the arbiters of the defensive back room, with Bethea, 35, having final say in a strict kangaroo court that issues fines for anything from MEs (mental errors), to TDs allowed, to MOBPs (missed opportunity for big plays). The grading is tough — especially for MOBPs, where just about any throw is deemed catchable for the young cornerbacks.

These are the dynamics of the defensive back room, where coordinator James Bettcher has tried to create natural competition. He distributes turnover trophies to reward big plays. Ballentine was the leader in the clubhouse entering this week. He also had an interception in the preseason opener, with an assist from Thomas, who provided prescient insight into the mindset of former Giants and current Jets quarterback Davis Webb.

Less than four weeks from the season, the collection of talent in the secondary seems just right. The three veterans are encouraged by what they see from the young players.

“The group that we got, great young men. They allow us to lead,” Thomas said.

Baker and the bunch have followed. Baker might be fearless, but he’ll have his struggles this season even if he’s destined to be a quality starter. Playing cornerback as a rookie comes with its ups and downs against the NFL’s top receivers.

“It’s going to be a huge challenge,” Bethea conceded. “He’s playing one of the toughest positions there is in the league … he’s a first-round draft pick. High expectations for him. He’s a Miami cat. So he already has that grit about him. He plays the game like the game is supposed to be played.

“He’s playing opposite [Jenkins], so he knows there is going to be times where they pick on him, stay away from [Jenkins], but those are the type of things that if you know going into the game, they are not going to be a surprise. He’s going to make some plays for us and I’m excited to see him out there.”

So are the Giants, especially after last week’s scare, which would have left them without the rookie they’re expecting to make the most immediate impact.