Before we concentrate on what Wayne Gallman is, we must get out of the way what he is not.

He is not Saquon Barkley.

“I don’t worry about all that,’’ Gallman said after practice. “I’m me and you’re all gonna see that.’’

The Giants need a replacement for their star running back. While the team was working on Wednesday, Barkley was in Green Bay getting a second opinion on the right high ankle sprain expected to keep him out 6-8 weeks. Gallman is next in line and will make the third start of his three-year NFL career on Sunday against the Redskins.

“It’s a big opportunity,’’ Gallman said. “It’s unfortunate for my brother to go out but this is what I prepare for. I’m ready for it. I’m not going to talk too much. I know I can do whatever is needed to help this offense win.”

Gallman, 24, usually gets one or two series a game and almost never has the luxury of back-to-back-to-back touches to get a feel for the game and find the rhythm so many running backs deem as critical to their success. Such is the burden of backing up a superstar.

After Barkley was injured late in the second quarter of the 32-31 victory in Tampa, Gallman took over and carried the ball five times in the second half, gaining only 13 yards. The Giants were playing from behind, down 28-10 at halftime, and had to throw it (17 times) a whole lot more than they ran it (seven times).

Gallman arrived in 2017 as a fourth-round draft pick from Clemson, served as the primary backup to starter Orleans Darkwa and was fairly productive and busy as a rookie with 111 rushing attempts and 476 yards. Things changed when Barkley moved in and Gallman’s workload decreased in 2018, to 51 rushing attempts for 176 yards.

Now the Giants have nowhere else to turn. Eli Penny is a fullback and Jon Hilliman, a rookie, is expected to be signed off the practice squad.

“You don’t cancel the game because one of your guys is not there,’’ coach Pat Shurmur said.

No, you do not. You put Gallman in for Barkley in the backfield with rookie quarterback Daniel Jones.

“He’s kind of a twitchy guy, he does a good job of getting it up in the hole,’’ Shurmur said of Gallman. “He’s got good collision balance. He’s improved catching the ball. He’s good with our pass protection. He’s a good all-around player and he’s going to be asked to do more.’’

Gallman won a national championship at Clemson and ran the ball 676 times for 3,429 yards in his three-year college career. His chance to move up the depth chart with the Giants ended the moment Barkley was taken with the No. 2 pick in the 2018 NFL Draft. The only way for him to get his shot is the way he is getting his shot.

“I knew at some point [Barkley] could probably get hurt and I would always have to be ready,’’ Gallman said.

What this means to him is obvious.

“I finally get to get some touches,’’ he said, smiling.

No one is expecting Gallman to be Barkley.

“You lose a special player like that it’s definitely tough, you hate to see it,’’ tight end Evan Engram said. “It’s simple. Guys got to step up.’’

It’s simple. Gallman has to step in.

“Even in the games when he gets his opportunity he tries to make the most of it,’’ Engram said. “He’s a hard runner, never goes down on the first hit, he always finds ways to fight for yards. I know he will be ready.’’