Matt Cassel has agreed to a contract with the Detroit Lions to back up starting quarterback Matthew Stafford, a source confirmed to ESPN.
The news was first reported Wednesday by NFL Network.
The Lions also have quarterback Jake Rudock on their roster. The team waived quarterback Alek Torgersen on Wednesday.
The Tennessee Titans released Cassel on March 9 after the quarterback served as a valuable veteran mentor and backup for quarterback Marcus Mariota over the past two seasons.
In his two seasons with the Titans, Cassel played six games (two starts), completing 55 of 93 pass attempts for 446 yards, three touchdowns and four interceptions.
He's seen the roller coaster of a career that had him as a longtime backup for Tom Brady in New England to a big-money starter in Kansas City to his current role as a journeyman backup.
Cassel, 35, was traded with Mike Vrabel, now the Titans' head coach, from the Patriots to the Chiefs in 2009.
He has passed for 17,499 yards with 104 touchdowns and 81 interceptions in 106 games (81 starts).
ESPN's Cameron Wolfe contributed to this report.