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NFL teams return to the practice field in late July for training camp—a crucial period that establishes the pecking order at multiple positions across the depth chart.

Every year, we see players improve by leaps and bounds, elevating their statuses from reserves to starters. Backups, developing talents and middle-to-late-round draft picks have opportunities to claim a contested spot in the first unit.

Last offseason, the Carolina Panthers lost All-Pro left guard Andrew Norwell during free agency. Leading up to the 2018 campaign, Greg Van Roten had played 20 games since going undrafted out of Pennsylvania in 2012; he took over the starting job.

Coming into the league as a fifth-round pick, defensive back Tre Flowers transitioned from safety at Oklahoma State to a starting cornerback for the Seattle Seahawks.

Van Roten and Flowers entered training camp as potential candidates to win position battles, but they didn't carry much buzz because of inexperience as a starter or draft placement.

We'll take a look at rookies and veterans who may rise to the challenge in a camp battle and become a surprise starter this summer.

Rookie first-round picks enter the league with high expectations, so they're excluded from the following selections. With the increasing number of starting slot wide receivers and cornerbacks, both positions are included below.