SAN DIEGO -- In the training camp battle for the starting right guard job -- left open with last year's starter Jeromey Clary still on the physically unable to perform (PUP) list -- a player has nudged ahead with two games left in preseason play.

Johnnie Troutman.

The Penn State product's name is listed as the starting right guard on the San Diego Chargers' depth chart as the team heads into the all-important third preseason game at San Francisco. In a training camp battle with rookie third-round draft pick Chris Watt, Troutman has had to put in work in order to earn the distinction of starting this week against the 49ers.

At the beginning of training camp, Watt showed the he could pick up the offensive blocking schemes quickly and put it to use at game speed. Watt also looked solid in pass protection, and appeared to be the better conditioned linemen of the two.

But an apparent head/neck injury suffered during practice by Watt opened the door for Troutman, who got the start against the Seattle Seahawks over the weekend, playing solid against one of the best defensive fronts in the NFL.

Troutman's performance was much different than his effort against Seattle during preseason play in 2013, as he struggled to stay in front of talented Seahawks defensive lineman Michael Bennett in his first game action after missing all of his rookie season in 2012 with a torn pectoral muscle.

"It was a little rough on me," Troutman said about the game against Seattle last year. "But I definitely did a lot better against them in this previous game."

Troutman started in nine games, along with San Diego's AFC divisional playoff against the Broncos, last season. So he's battled tested. At 6-4 and 330 pounds, Troutman also pairs with D.J. Fluker (6-5, 339 pounds) to form one of the biggest right sides of an offensive line in the NFL.

Chargers head coach Mike McCoy says he likes what he's seen so far from Troutman.

"He's done a nice job I think, overall," McCoy said. "From time to time, there's a breakdown, but that's every player. I think the more he plays, the more comfortable he gets."

Troutman's starting role is definitely written in pencil instead of pen. He'll continue to rotate at right guard in practice with Watt, and when Clary is finally healthy, he'll be added to the competition.

But on Sunday, Troutman's gets another important opportunity to continue to build chemistry with Fluker and the rest of San Diego's starting offensive line.

"I'm feeling good," Troutman said. "Every day is a grind to just get better, so it's just taking baby steps. There's plays here and there every day in practice that you pick out that you want to do better on. But the whole thing about it is to have more good plays than you have bad."