Left tackle Trent Williams was back in the starting lineup on Sunday after missing two games with a sprained ankle, and he was the culprit on a personal foul that stalled what was a promising drive early in the second quarter of a 19-11 loss to San Francisco.

Officials charged Williams with unnecessary roughness for shoving San Francisco defensive tackle Justin Smith in the back. Making matters worse, wide receiver Jabar Gaffney had caught a 10-yard pass from John Beck immediately before the foul, plus linebacker Ahmad Brooks was offside, meaning the Redskins would have gotten a first down with the free play.

Washington instead faced third and 23 from its 34 because by rule, the personal foul takes precedence for enforcement.

“We’re defending ourselves,” said Williams, who added he never heard the whistle blow and that he simply was coming to the aid of right guard Maurice Hurt. Smith “initiated contact. I mean he was playing through the whistle. We’re playing through the whistle, so I mean, I don’t know. I don’t got no comment on it. It is what it is.”

It’s not the first time this season Williams has been flagged for a similar infraction. Three weeks ago before he was injured against Philadelphia at FedEx Field, Williams was called for a personal foul when on a play in which starting left guard Kory Lichtensteiger tore his ACL and was lost for the season.

Williams said afterward he felt Eagles linebacker Darryl Tapp had tossed Lichtensteiger to the ground, yet officials didn’t issue a penalty. That’s when Williams shoved Tapp and was called for unnecessary roughness.

“It was getting physical with the guy after the play,” Hurt said of the incident against San Francisco. “He was being a teammate. That’d be what I would do for him. They always get the second guy. Never get the first guy. That shows you the closeness of our unit. He was defending me and sending the message that we won’t have nobody taking shots on nobody.”