Jarret Johnson reaggravates hamstring

SAN DIEGO -- The San Diego Chargers’ best pass-rusher, Jarret Johnson, could be watching from the sidelines again.

Johnson had missed two games due to a hamstring injury, but returned to the field against Washington last week. However, Johnson suffered a setback at practice on Thursday, and did not practice on Friday.

Johnson is listed as questionable on San Diego’s injury report. If he can’t go, the absence of a veteran defender like Johnson could be a significant blow for a defense facing the top-rated passing offense in the NFL.

“We’ll take it day-to-day,” San Diego coach Mike McCoy said. “We’ll see how he is on Sunday morning, and we’ll go from there.”

Thomas Keiser likely would be the next guy up if Johnson can’t play. Keiser said even with cornerstone left tackle Ryan Clady done for the season with a foot injury, Denver’s offensive line has done a nice job protecting Peyton Manning. The Broncos allowed only 11 sacks this season, second best in the NFL. Keiser has two sacks on the year.

“Their offensive line is talented,” Keiser said. “And we’ve had time to look at them, scout them out. At the end of the day, it comes down to one-on-one matchups. So whether there’s three, four or five guys rushing, it doesn’t matter who you’re going against, because you’re going to have a battle. And you need to win it.”

Along with Johnson, offensive lineman Mike Remmers (ankle), receiver Eddie Royal (toe) and defensive end Lawrence Guy (toe) did not practice. Remmers has been ruled out for Sunday. Royal and Guy are questionable.

Royal has not practice the past two weeks leading up to San Diego games, and he’s still played.

McCoy said he’s not concerned about Royal experiencing timing issues with Philip Rivers because he’s not getting consistent reps with the starting quarterback each week. Royal’s totaled eight receptions for 125 yards and two touchdowns in his last two games.

“Not as of right now I’m not,” McCoy said. “The way he’s played the past, couple weeks doing this, there’s certain things that we are doing during the practice that he and Philip communicate on to make sure they are on the same page with everything. He’s out there watching every snap, doing whatever he can do and catching balls on the side.”

Out for the past three games with a groin injury, linebacker Donald Butler made it through practice this week and is probable for Sunday, along with offensive lineman Chad Rinehart (toe), punter Mike Scifres (knee) and linebacker Tourek Williams (thumb).

“It’s been a hard couple weeks for him to not be able to play,” McCoy said about Butler. “But he’s done everything he can to get back as soon as he can. So it will be good to have him out there.”