The Titans believe Young could miss two to four weeks with a sprained left knee, sources told ESPN's Chris Mortensen. The team suspects he suffered damage to his medial collateral ligament.
Tennessee coach Jeff Fisher did not have the results of the tests on Young's knee when the coach met the media on Monday afternoon. Fisher promised that results will be shared once available.
Fisher said if the injury is a third-degree MCL sprain, Young could be out a couple of weeks. But he reiterated the Titans don't know yet.
Young iced his knee and apparently felt good enough early that team officials said they thought he could talk to reporters. But he was moving very gingerly while trying to get dressed with crutches at his locker and left without talking to reporters.
He was hurt on a bootleg when Jaguars linebacker Daryl Smith collided with his left leg a couple plays after Fisher had to talk to his quarterback about whether he could go back into the game. Young had thrown his helmet on the sideline after being intercepted for the second time, and he didn't have his helmet with him when the Titans got the ball back.
Backup quarterback Kerry Collins appeared to be going in, and Fisher took his headset off and talked with Young, who then pulled on his helmet and went into the game.
Fisher said the discussion involved only Young's hamstring and whether he felt physically able to return.
"Regarding the hamstring, he said, 'It's tight,' and I said, 'If it's tight, we'll go with Kerry and try to talk him back into it' and he felt good," Fisher said. "When he got out there, he moved. He didn't have any issues with the hamstring on the bootleg on which he was hurt."
Young's second interception came a play after the Titans had picked off one of David Garrard's passes. Trimming interceptions is a key focus for Young this season after being picked off 17 times with only nine touchdown passes in 2007.
Asked if he was disappointed with Young's attitude, Fisher said no.
"He's very competitive," Fisher said. "I've never seen him jump up and down and high-five his teammates after he throws an interception."
The Titans have been contacting free-agent quarterbacks, sources told Mortensen, including Chris Simms. Simms is scheduled to be in New England on Monday to work out for the Patriots and has no immediate plans to visit Tennessee.
The Titans have only veteran Collins on the roster. Ingle Martin is on their practice squad. Asked about a report that Simms would be visiting Tennessee, Fisher said not to his knowledge.
Information from The Associated Press and ESPN's Chris Mortensen was used in this report.