The San Diego Chargers signed QB Kyle Boller to a one-year contract on Friday after second string QB Charlie Whitehurst exited Thursday evening’s practice with a sore left knee (MCL).

Whitehurst missed a walk-thru Friday morning. After practice he was seen wearing a wrap and a brace on the knee. “It’s sore now,” Whitehurst said. “I think in a couple weeks it will be fine.”

Boller played in two games with one start for the Raiders in 2011. He threw three INTs and had three fumbles (none lost) with no TDs and just 161 yards passing. Boller will serve as an insurance policy through training camp and will likely see playing time during the first two preseason games against the Packers and Cowboys.

QB Jarrett Lee (undrafted, LSU), who mostly observed during OTAs and minicamp, took on Whitehurst’s snaps during the two practices. “You never want that to happen to a teammate,” Lee said. “Especially a guy like Charlie, he has been very good to me. But, the opportunity has been great to get in there and get some live reps.”


Follow Chargers reporter Dan McLellan on Twitter @CBSSportsNFLSD and @SanDiegoSports