The status of King Dunlap is "up in the air," a source said Tuesday.

The Chargers left tackle has been diagnosed with a neck strain. That much is known. But as that injury is further evaluated on a player with two confirmed concussions this year, it is difficult to tell just how long Dunlap will be sidelined.

He didn't play the second half Sunday against the Broncos because of the neck injury.

An early report from San Diego's sideline was that Dunlap had a concussion, but that determination was the team erring "on the side of precaution," coach Mike McCoy said Monday. He added the team has neither verified nor ruled out a concussion, which would be Dunlap's third in less than two months.

While sorting through the situation, the Chargers brought in tackle Willie Smith for a free agency visit Tuesday. Dunlap is receiving a second opinion on his MRI.