COSTA MESA, Calif. (AP) Los Angeles Chargers quarterback Philip Rivers is in the NFL's concussion protocol after experiencing possible symptoms of a head injury, endangering his streak of 194 consecutive starts since 2006.
Rivers told the Chargers about his symptoms Monday after they returned from a 20-17 overtime loss in Jacksonville, coach Anthony Lynn said.
The Chargers (3-6) are still hopeful Rivers can play on Sunday when they host the Buffalo Bills, but they will be cautious with the health of one of the most durable quarterbacks in NFL history.
''He needs to pass the test first,'' Lynn said. ''If he's not healthy, we do not want him on the field. But if he's healthy and ready to go, then (he'll play).''
Rivers wasn't sacked by the Jaguars, but he was hit five times and pressured regularly. Lynn wasn't certain when Rivers was hurt, but the quarterback took a big shot when he threw a long interception in overtime.
Rivers is the foundation of the franchise that moved to the Los Angeles area this year. He spent his first two NFL seasons as the understudy for Drew Brees, but the North Carolina State product has started every game in the regular season and the playoffs for the Chargers since he became their starting quarterback in the 2006 opener.
''I don't even really have an experience with him not being out there,'' said tight end Antonio Gates, Rivers' teammate since 2004.
''I'm pretty sure they'll go through the right steps in the protocols to try to get him back on the field. His health is the main concern. ... That's speaking from a personal standpoint as a friend, just making sure he's healthy enough to go out and play and help us win.''
With 185 straight regular-season starts and nine playoff starts, Rivers has the fourth-longest streak for a quarterback in NFL history.
Brett Favre set the NFL record with 321 starts from 1992-2010. Peyton Manning made 227 consecutive starts from 1998-2011, while the New York Giants' Eli Manning has a still-active streak of 220 straight starts since November 2004.
Rivers is 10th in NFL history with 48,096 yards passing in 14 seasons with the Chargers. While they have struggled in recent seasons, Rivers and Gates led the Chargers to four straight AFC West titles from 2006-09, along with the 2007 AFC championship game.
Rivers has passed for 2,263 yards this season with 15 touchdowns and seven interceptions, completing 60.1 percent of his 323 throws. Nobody else on Los Angeles' roster has thrown a pass.
If Rivers can't play Sunday, Lynn says he is confident in backup Kellen Clemens, who hasn't started an NFL game since 2013 with the St. Louis Rams. Although he is well-versed in coordinator Ken Whisenhunt's offense, Clemens has barely played over the past 3+ seasons with the Chargers, throwing just 10 passes and getting most of his field time as a kick holder.
''I feel fine about Kellen,'' Lynn said. ''He's well-prepared. He's a veteran. Obviously, I'd rather have my starter in there. But if something happen with Phil, we'll go with Kellen.''
The Chargers don't have to decide until Sunday morning whether Rivers will play, and Lynn didn't seem anxious to make a quick decision this week.
''Philip is obviously the cornerstone of what we do and how we implement our game plan,'' Gates said. ''But I'm quite sure that we'll do things that maximize Kellen's ability if need be.''
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