JACKSONVILLE – Let the battles continue …

That's a primary theme for the Jaguars entering the 2015 preseason opener against the Pittsburgh Steelers at EverBank Field Friday, because while training camp matters when it comes to competition for starting roles, nothing quite compares to what happens in a game.

And the first game competition for several key roster battles comes Friday.

This week's unofficial depth chart – the first released by the team this season – contained four positions with "co-starters:" center, running back, defensive tackle and cornerback. And while many of the players battling will play significant roles no matter the outcome, there are still starting spots to be decided and roles to be determined.

How will they play out? That question starts getting answered Friday.

A look at five position battles entering the preseason:

1)Three-technique tackle: Ziggy Hood versus Tyson Alualu.This battle has a temporary feel because the winner is probably holding a spot until Sen'Derrick Marks returns to full health from offseason reconstructive knee surgery. Still, it's important because Marks' status for the September 13 regular-season opener likely will be uncertain until shortly before the game. Hood was the backup at the spot last season, but Alualu performed well at the strong-side end spot last season and has performed well in training camp. Edge: Alualu.

2)Cornerback, Aaron Colvin versus Demetrius McCray.This is similar to the three-technique spot in the sense that no matter the outcome, both players almost certainly will play an extensive role. And there really may never be a clear "winner" in this spot. Colvin, a second-year veteran, appears likely to play extensively at outside corner and at the nickel – perhaps starting at the outside spot and moving inside in passing situations. That would technically make him the starter over McCray, but McCray would be on the field at outside corner in passing situations. Realistically in the NFL you need at least three corners capable of starting. McCray, Colvin and Davon House give the Jaguars that. Edge: Colvin.

3)Running back, T.J. Yeldon versus Denard Robinson.This is probably something of a temporary battle, too; Yeldon realistically was selected in the second round of the 2015 NFL Draft to be the bell-cow, No. 1 running back at some point. Considering his talent level and performance in camp thus far, that time likely will be soon. Yeldon has looked very good in the offseason program and in training camp, and many in the organization were relieved when the finger injury he sustained in the scrimmage was minor. Robinson, who was very productive as a starter for a four-game stretch last season, has looked very good in camp and has earned a prominent role. The guess here is that role will be as a backup to start the season, but it wouldn't be a shock if the Jaguars started Robinson early in the season with Yeldon getting most of the carries. Either way, Yeldon appears likely to be the guy very soon. Edge: Yeldon.

4)Center, Stefen Wisniewski versus Luke Bowanko.This battle is tight and has a more permanent feel than the first three. The Jaguars liked what Bowanko showed in 14 games as a rookie starter last season, but they brought in Wisniewski as an unrestricted free agent from Oakland in the offseason to provide experience and competition. Wisniewski started the past four seasons in Oakland, and that experience is big. The two have split practices working with the starting lineup throughout training camp and it stands to reason they could split starts in the first two preseason games. Wisniewski's experience could give him the edge and Jaguars Head Coach Gus Bradley spoke highly of him this week. Still, this hasn't been remotely decided yet. Edge: Wisniewski.

5)Left guard, Zane Beadles versus A.J. Cann.This is far from decided, but it does have a matter-of-time feel to it; the Jaguars didn't draft Cann in the third round of the 2015 NFL Draft to have him sit on the bench long. The question: What is long? Will he be a reserve all season? Part of the regular season? A preseason game or two? Beadles struggled at times last season, but improved late and has the edge in experience and savvy. Those are important things on the interior of the offensive line. Cann fits what the Jaguars want from their gap-blocking, run-blocking approach and he has looked very good at times in training camp. The guess here remains that Beadles emerges from preseason as the starter, but there's a feeling that this battle keeps getting closer by the day.