It is not easy to admit it. 

It is not easy for an accomplished college player to come out and reveal he did not quite have it the first time he took the field in an NFL game. 

Eric Gray is not most rookies.

He knew what he was able to do, realized what he did not accomplish and was honest with his self-appraisal of how he fared in his preseason debut for the Giants. 

“First game you’re just trying to get your feet wet, you’re just trying to make an impression,’’ Gray told The Post. “It’s just a different environment, you’re trying to see where you fit in.’’ 

Gray spoke this past Friday night, not long after his second stab at it was appreciably better.

His one highlight as a running back was muscling his way in on a 9-yard touchdown run in the second quarter of a 21-19 victory over the Panthers at MetLife Stadium.

His best moments on special teams — where he has an immediate opportunity — was his decision-making on punt and kickoff returns. 

“This game I felt comfortable, more settled in, more like myself,’’ Gray said. 

The Giants want Gray to be himself. He averaged 5.6 yards on 549 rushing attempts in a four-year college career split between Tennessee and Oklahoma.

His 1,366 yards and 11 touchdowns last season for the Sooners launched him onto NFL draft boards and the Giants took him in the fifth round.

At 5-foot-10 and 211 pounds, he is shifty enough and strong enough to develop into a rotational running back.

The Giants believe he is a more-than-capable pass-catcher out of the backfield. 

First, though, Gray had to shake away the jitters. He did not look sure of himself, gaining only 9 yards on five rushing attempts in the preseason opener in Detroit. 

“I think he is a rookie that needs to play and get experience playing,’’ coach Brian Daboll said after that performance. “With all the rookies, I’m sure there was, like there always has been since I’ve been in the league, there is a little bit of anxiety. They are anxious to get out there and play in their first game.” 

Gray’s first impact on offense came in the second quarter in his first game at MetLife Stadium.

From the Panthers’ 9-yard line, Gray picked up strong blocks from rookie center John Michael Schmitz and second-year tight end Daniel Bellinger to get him halfway to the end zone.

The rest, Gray had to do on his own.

Gray put his head down, moved the pile and surged forward against defensive lineman Alim McNeill.

To get into the end zone, Gray got low, stretched his arms and was able to carry safety Kerby Joseph the final yard for the touchdown. 

“That’s important, you have to get the ball downhill, particularly down there in the red zone and run with good pad level and leg drive, got to block it up well,’’ Daboll said. “The space is condensed. There are more guys in the box, there is usually an extra guy you are going to have to either run through or run around. It was good to see him be able to finish the play in the end zone.” 

For Gray, this was a step up from his tentative opening game. 

“You can see I’m a hard-nosed runner, like on the touchdown that I scored, being able to get in space and make people miss,’’ he said. “You had to bow down and get in there.” 

Saquon Barkley and Matt Breida are ahead of Gray on the depth chart on offense.

As long as he shows he will not put the ball on the ground, the return game is where Gray as a rookie will earn a uniform on game day. 

He raced forward for a fair catch of a punt in the first quarter against the Panthers, saving yards by not letting the ball bounce.

Gray alertly signaled for the return team to get out of the way because the punt was falling short. 

In the second quarter, he smartly did not field a kickoff that bounced inside the 5-yard line and then rolled out of bounds, resisting the fear that the ball might roll dead inbounds. 

“If it would have bounced on the 1 [-yard line] I just would have stuck my foot out of bounds and touched it and then it would have been the same thing as out of bounds,’’ Gray said. “I know the little tricks of the trade.’’ 

That was impressive. 

“Made some good decisions there,’’ Daboll said. “The more he does it, the better it is.”