ALLEN PARK, Mich. -- Detroit Lions defensive coordinator Cory Undlin will be calling the defensive plays for the franchise this year, the first time the 49-year-old will call plays in the NFL.

Whether the Lions would use Undlin or head coach Matt Patricia as the defensive playcaller had been a continued question since Undlin's hiring in January following the retirement of Paul Pasqualoni after the end of the 2019 season.

Patricia had taken over at least part -- if not all -- of the defensive playcalling last November when the club's defense had turned into one of the worst in the league, allowing 284.4 passing yards per game and 400.4 yards per game total.

"There's nothing really to hide here," Patricia said. "Cory has been grinding away. He's our defensive coordinator. He's been working to understand everything we're doing defensively and obviously has his input and Cory and I have known each other a long time.

"Certainly without the spring, it was going to be interesting to see how training camp went and the operation and all that. He's ready to go. He's ready to call it and do what he's got to do."

Patricia said that, as the head coach, he might jump in if there's something he wants to call. Both Patricia and Undlin will work on the sideline together this fall instead of Undlin being in the booth.

Undlin said he prefers to be on the field because "there is a feel of being on the field and any time when you got to go through another conduit to get it out there, it's more efficient for me." He also wants to be able to look at his players when he's coaching them.

The Lions hired Undlin from Philadelphia, where he was the Eagles' defensive backs coach from 2015 to 2019 -- including when Nick Foles was Philadelphia's quarterback. His first test as a playcaller may come against Foles in the regular-season opener if Foles beats out Mitchell Trubisky for the Bears' quarterback job.