This year's team for HBO's series Hard Knocks is the Oakland Raiders. So far, there hasn't been a shortage of material due to Antonio Brown and Jon Gruden.

Brown showed up to training camp in a hot-air balloon to the dismay of his fiery head coach. A few days after the balloon spectacle, Brown began missing practices due to injuries to his feet.

The injury stemmed from a cryotherapy machine, causing him to get frostbitten feet. Along with his feet, Brown has an ongoing issue with the helmet he will wear for the upcoming season.

In the meantime, the Raiders have had to carry on without their highly-touted wide receiver in the preseason. Through two preseason games, Oakland has won both games against the Los Angeles Rams and Arizona Cardinals.

Unfortunately for Gruden, wins in the preseason don't carry over into the regular season. The Raiders will have two more exhibition games to prepare themselves for the 16-game season.

Here are three players to watch when the Raiders square off against the Green Bay Packers in their third preseason game.

3. Keelan Doss

Among the players who are competing for a spot on the 53-man roster is Keelan Doss. The California native arrived with the Raiders as an undrafted rookie out of UC Davis.

After being snubbed in this year's draft, Doss is set to prove himself worthy of making the team in 2019. Currently, the undrafted rookie is competing with a few others to secure spots at the wide receiver position.

Through two preseason games, the 23-year-old wideout has caught eight passes for 47 yards and a touchdown. Doss's lone touchdown came in the Raiders' preseason debut against the reigning NFC champion Rams.

With two games remaining, the clock is ticking for Doss to display to the coaching staff that he can be a difference-maker on the roster. The next chance he will get to showcase his talent will come against the Packers.

2. Arden Key

It's a touchy subject: the Raiders and their pass rush. That's because they proceeded to trade their best pass rusher, Khalil Mack, prior to the 2018 season.

As a result, the Raiders struggled to find their way to the quarterback, totaling an astonishingly low 13 sacks in 2018. Oakland was last in the NFL in sacks last year. This season, the Raiders are focused on improving their pass rush.

The Raiders used one of their many first-round picks to select Clelin Ferrell out of Clemson. Aside from Ferrell, the team is relying on Arden Key to provide some pressure for the defense.

Key was the Raiders' third-round selection in the 2018 NFL Draft. Last year, the LSU product started in 10 games but was able to amass just one sack, four tackles for loss, and 11 hits on the quarterback.

So far in the preseason, Key has shown some adjustments in his game with three tackles and one sack. The second-year defensive end will want to continue his play in the Raiders' final two preseason contests.

1. Mike Glennon

One of the most underrated competitions going on with the Raiders is the battle between Mike Glennon and Nathan Peterman for the backup quarterback job. As it currently stands, Glennon has the edge but nothing is set in stone.

In Oakland's preseason opener against the Rams, Glennon was sporadic, completing 17 of his 25 passing attempts for 200 yards and two interceptions. Turnovers are one way to lose your job; his two interceptions definitely didn't help his cause.

Surprisingly, Peterman thrived in his preseason debut with 66 yards through the air and 56 yards with his legs, including a 50-yard run. The former Buffalo Bills quarterback was inching closer to winning the job.

Then, in Week 2 of the preseason, Glennon impressed with 175 yards and two scores while completing nearly 80% of his passes. On the other side, Peterman completed all eight of his attempts but managed only 41 yards through the air.

In the last two preseason games, Glennon will need to limit the turnovers and run the offense efficiently to secure the backup job behind Derek Carr.