Casey administered a late verbal shot at the Jaguars quarterback on 104.5 The Zone in Nashville (Tenn.) on Tuesday.
"As long as Bortles is back there, if the ballgame is in his hands, he's going to choke," Casey said.
The 28-year-old Casey's comments come on the heels of the Titans completing a regular-season sweep of their AFC South rivals with a 15-10 win on Sunday. Despite the loss, the Jaguars captured the division title.
"King of the South? King of the South? Sounds great, but gotta be able to beat us," Casey said on Sunday.
Casey did his best to soften the blow later on social media.
"Chill, y'all. I was just hyping our defense," he wrote on Twitter. "If we put the pressure, some QBs will choke."
Titans safety Kevin Byard intercepted Bortles twice on Sunday en route to being named the AFC Defensive Player of the Week.
Bortles completed just 15 of 34 passes for 158 yards on Sunday. He has one touchdown pass and four interceptions in two encounters this season with Tennessee.
Tennessee visits the Kansas City Chiefs for a wild-card game on Saturday (4:35 p.m. ET) while Jacksonville hosts the Buffalo Bills on Sunday (1 p.m. ET). The Titans and Jaguars could only meet in the playoffs if both teams advance to the AFC Championship.