The MRI exam results came in and revealed -- pretty much as expected -- that Titans quarterback Vince Young sprained the medial collateral ligament in his left knee Sunday against the Jaguars.
The Titans are not giving a timetable for his return. Normally, a medial collateral ligament strain could take four to six weeks to heal, but quarterbacks can return in two to four weeks because the style of their game is different from that of running backs or cornerbacks, for example. Vikings quarterback Tarvaris Jackson bounced back from an MCL tear and played two weeks later.
Titans coach Jeff Fisher said only that Young would be out this week.
Young left the field Sunday on a golf cart and had to be assisted to the locker room. Because he couldn't put any weight on the left leg, he had to use crutches to leave the stadium.
Until he returns, Kerry Collins will be the starting quarterback.
On Wednesday, the Titans announced they had agreed to terms with former Buccaneers QB Chris Simms.
"Chris has been a starter in the league and should fit into our system well," Titans general manager Mike Reinfeldt said in a statement. "He is a smart player who is a student of the game and has the presence in the huddle that you look for in quarterback."
The Titans also waived tight end Dwayne Blakley from the 53-man roster to make room for Simms, and added quarterback Preston Parsons to the practice squad.
John Clayton covers the NFL for ESPN.com. ESPN.com's Paul Kuharsky contributed to this report.