EAST RUTHERFORD, N.J. – It will be five starting offensive line combinations in five games for the Giants when they face the Miami Dolphins Sunday in Hard Rock Stadium.

That was assured when the rookie center John Michael Schmitz was declared out of the game because of the shoulder injury he suffered Monday night against Seattle. He had started each of the first four games.

In addition to Schmitz, stellar left tackle Andrew Thomas will miss his fourth consecutive game with a hamstring injury, guard Shane Lemieux will be sidelined with a groin injury, also suffered Monday.

The good news for the Giants is that running back Saquon Barkley is listed as questionable. Barkley, who was limited in practice, has missed the last two games with an ankle sprain. Before the Seattle game he was listed as doubtful, a designation that almost always results in the player not suiting up. The questionable listing – and the fact that Barkley took team reps in practice this week – is proof Barkley has improved.

Speaking prior to practice, coach Brian Daboll did not commit to Barkley playing.

"He's practiced," Daboll said. "He's done stuff in team and some individual stuff. So, I think he's made progress. We'll just give him another day and see where he's at."

The O-line has not been in the same place twice this season, though a trio of second-year pros has provided some stability. Right tackle Evan Neal will be the only lineman to start each of the first five games. Right guard Marcus McKethan and left tackle Joshua Ezeudu will each start their fourth consecutive game.

Ben Bredeson, who missed the Week 3 game in San Francisco with a concussion, started for the third time at left guard vs. the Seahawks. But when Schmitz went down on the Giants' first offensive series, Bredeson moved to center, where he will start Sunday. Lemieux took over at left guard, but was injured in the second half and replaced by Mark Glowinski.

Daboll said the coaches would "talk after practice" about left guard, but since Glowinski is the only other healthy interior lineman on the 53-man roster, it is logical to assume he will start. Glowinski played the season opener at right guard – where he started all but one game last season – but was replaced by McKethan in Week 2.

If the Giants need reinforcements for the game, they can elevate linemen Jalen Mayfield and Jaylon Thomas from the practice squad.

The line will regain some much-needed stability when Thomas, its best player, returns to the field. The Giants have not put him on injured reserve, an indication they are hopeful he can suit up soon. But Thomas admits he's mystified by his potential timetable.

"I really don't know," he said. "They tell me day to day and that's the approach I'm taking. The soft tissue can make you feel great, or you could not. So, just trying to do everything I can to see if I'm able to play."

Thomas was hurt early in the season opener against Dallas on the play in which the Cowboys blocked Graham Gano's field goal attempt and Noah Igbinoghene returned the ball 58 yards for a touchdown. He remained in the game and played 53 snaps but hasn't played since.

"The adrenaline of the game, I'm just going," Thomas said. "Obviously, it was sore when I hurt it. But at that point, we were down by seven. … So, in my mind, I'm gonna compete and even when we were down, my mindset is if I can go out there, I'll try until they pull me out. That's just the mentality I have."

Thomas tried to practice last week but was quickly removed from all drills.

"When I went to practice, my mindset was like I don't know because I haven't been out there," he said. "When I got out there and was moving around, I felt it, I just wasn't ready yet and they could see it as well. So that's why they took me out."

Glowinski, meanwhile, is happy to be back in.

"I look at it as an opportunity to play and to help the team, to make sure I do everything I can to be available for the situation that's presented right now. I don't know what's to come. I just prepare and do whatever I can to put myself in this situation."

Glowinski played all 70 offensive snaps in the season-opening loss to Dallas. He didn't start the following week in Arizona, but played 37 snaps after Bredeson was injured. Four days later, Glowinski never left the sideline in San Francisco.

"I tried to mimic some of the feeling of the game on our off day, doing a lot of conditioning and a lot of movement and trying to get the cardio that I would have for the game," Glowinski said, "to be prepared for the following week for whatever happens."

What happened was Lemieux was injured on Monday and Glowinski was called on to play left guard in the second half. He has started 18 games there, including two in the postseason.

"I just have to give myself a friendly reminder on where I am and just make sure I understand my hand placements and all those kinds of things," Glowinski said. "That was a big majority of what my thought process was throughout the week, making sure that I was dialed in on what the plays were."

The season opener was Glowinski's 98th career start, including seven in the postseason. He started at least 14 games in each of the previous four seasons. To be told he was out of the starting lineup was a tough pill to swallow.

"There is that competition within you that they want to keep going and all that," Glowinski said. "But it's always what the team decides on doing; they're the employer at the end of the day. During that week, we were still taking a majority of reps and everything like that. We were still training and getting ready for what was to come the following week.

"That's how the last couple of weeks have been. It's not going to change my preparation, the way that that I eat, the way that I study, just the way that I go about everything. I make sure I'm focusing on all those things."

*In addition to Barkley, tight end Daniel Bellinger (knee) and linebacker Micah McFadden (ankle) were limited in practice and are listed as questionable.