Cincinnati Bengals quarterback Joe Burrow is on the mend after undergoing appendix surgery earlier in the offseason. With Burrow sidelined, the defending AFC champions Bengals started Burrow's backup Brandon Allen in the team's first preseason game against the Arizona Cardinals.

Unfortunately for the reserve passer, he went into concussion protocol, according to ESPN's Adam Schefter. Allen was later ruled out after he indeed suffered a concussion. He was ruled out for the rest of the Bengals game and replaced by former Washington Huskies passer Jake Browning.

The Bengals, of course, don't have a quarterback controversy with superstar signal-caller Joe Burrow as the team's franchise quarterback, but Cincinnati does have a battle for the backup spot. Allen's injury will surely hurt his chances to hold onto the job.

Allen wasn't the only injury for the Bengals, either. Tight end Mitchell Wilcox, who started with Hayden Hurst and Drew Sample sitting out, was ruled out with an ankle injury while reserve defensive tackle Tariqious Tisdale was injured after making a tackle.

A former sixth-round pick out of Arkansas, Brandon Allen is already on his fourth NFL team. He previously played for the Jacksonville Jaguars, Los Angeles Rams and Denver Broncos. In nine career starts in four seasons, Allen is 2-7 with 10 touchdown passes and six interceptions.

The Bengals will have plenty of time to get their passers healthy, though. Cincinnati opens their AFC conference defense against the Pittsburgh Steelers on Sept. 11. They'll next take the field against the New York Giants on Aug. 21.