When the Cotton Bowl matchup of Oklahoma and Florida was announced (Dec. 30 at 8 p.m. ET on ESPN/ESPN App), it was fun to think back to the meeting between these two teams in the 2009 Orange Bowl and the BCS National Championship Game. Dan Mullen was even on the sideline for the Gators as offensive coordinator for the last time before moving on to coach Mississippi State.

It also happens to be the last time both of these teams played in a national championship game.

Mullen is back at Florida now as the head coach, hoping to get the Gators back to national championship contention. Oklahoma has been in the hunt plenty of times since losing to Florida in the Orange Bowl but has not yet captured a title, even after making three straight College Football Playoff appearances before this season.

So what should we expect in the 2020 matchup?

It would be easy to think about offense first because of what Lincoln Riley has brought to the table as Oklahoma’s coach and how Mullen has transformed the Gators over three years at the helm. But how the defenses prepare for each other could end up being the key.

Florida has struggled on defense all year, leading to speculation about defensive coordinator Todd Grantham’s job security, though Mullen said Grantham will coach in this game. Oklahoma has made strides with its defense this year, allowing only 21.8 points per game — its lowest average since allowing 22 points a game in 2015. And while Oklahoma plays in the Big 12, the Sooners have not faced an offense as prolific as Florida’s this season.