Kelvin Sheppard is likely to be a starting linebacker on Sunday in San Francisco

EAST RUTHERFORD, N.J. –Five days ago, Kelvin Sheppard was just another NFL fan sitting in front of a television, watching several games on television. On Sunday, he might start at middle linebacker when the Giants visit the San Francisco 49ers.

Even if he doesn't start, Sheppard should play a significant role just days after wondering if he would find a job in the league this season. How, exactly, did this happen?

"They literally called me (on) Monday," Sheppard said. "And they asked my agent if I would be willing to come up for a workout, and I was like, 'Yep,' and came up, worked out and they signed me after the workout."

Like many such opportunities in the NFL, Sheppard's resulted from injury. Or, more accurately, injuries. On the Giants this year, it's not just individual players who get hurt, but position groups. On Oct. 8, they lost four receivers, three for the remainder of the season. Now it's the linebackers who are going down en masse. Today, three of them were declared out of the San Francisco game – B.J. Goodson with an ankle injury and Devon Kennard and Kennan Robinson with quad injuries. Two more backers are questionable – Jonathan Casillas (neck) and Calvin Munson (quad).

This week, the Giants re-signed Deontae Skinner and Sheppard. Asked specifically about Sheppard, coach Ben McAdoo said, "He's going to have an opportunity to play."

It won't be a new experience. Sheppard played in every game, 11 of which he started, for the Giants in 2016. The team chose not to re-sign him, leaving Sheppard without a football team for the first time since he was a youngster.

"I took a few visits," Sheppard said. "I went a couple places and was down back in Miami working out, taking visits. I'd go to another team, come back, go to another team, come back. So it was a little busy, but not what I ultimately wanted. But I'm back where I wanted to be from the get-go."

During his enforced exile, Sheppard confirmed what he already knew, that watching football is not nearly as much fun as playing the game.

"I've played football 25 years," he said. "This is the first time I wasn't, so yeah, (I missed it)."

Although he kept close track of the NFL, Sheppard said, "It was hard to watch the Giants," because he wanted to play for them. Now he will.

Sheppard has spent this week reviewing Steve Spagnuolo's defensive schemes.

"It's more recall than actually learning the actual plays," he said. "It's more just recalling everything I already knew from last year."

It's possible he will wear a green dot on his helmet, meaning he will receive the calls from Spagnuolo via a small receiver in his helmet.

"I'm fine with that," Sheppard said. "The transition has been great. It's a great group of guys. Mostly a lot of guys I was already in there with. They've been helping me out, so I'm definitely fine with that."

The Giants are 1-7, but Sheppard has as much confidence in the team as he does in his ability to walk off the street and make a positive contribution.

"To be honest, I think we're going to win every game," he said. "That's just my mentality."

The Giants can use that positive thinking.

*Goodson will miss his fourth game this season and second in a row. Kennard has played in every game since the beginning of the 2016 season, and started seven of the eight games this season. Robinson had played in the last six games after missing the first two with a concussion.

*Three other players joined the five linebackers on the injury report. Cornerback Donte Deayon (ankle) is doubtful. Defensive ends Olivier Vernon (ankle) and Kerry Wynn (knee) are questionable.

Vernon has missed the last four games and Casillas the last three. McAdoo said each is "making progress," but he won't know until tomorrow's practice if they will play on Sunday.

"I'm feeling great, so we'll see how it goes on Sunday," Vernon said. "I'm taking it day by day. We got practice tomorrow, so we'll see how that goes and look forward from there."

Vernon didn't miss a game in his first five NFL seasons, so this hiatus has given him more of an appreciation for being on the field.

"I was thinking the other day, some of the guys in the building, some of the former Giant players that have been in here, and I could see from their point of view, their perspective, that dang, if they could just play another game, you know what I mean?" he said. "In my mind, I was like dang, is this how it feels to not play, and it felt weird to me. I'm just glad and I'm fortunate that it wasn't worse than what it could have been. So I'm just glad to be back and enjoy my time and enjoy my teammates."