The 49ers in the second half Sunday against the Eagles lost rookie defensive lineman Solomon Thomas with a knee injury, adding to a long list of key players sidelined.

Solomon, the third-overall pick in April, was the second first-round selection on defense to leave the game. Free safety Jimmie Ward left in the first quarter with a forearm injury that required X-rays. Leaving the game indicates Ward’s injury may be long term.

The 49ers also began the game without linebacker Reuben Foster, who missed his sixth game of the season. He entered the weekend listed as questionable after suffering a rib injury Week 7 against Dallas.

San Francisco also lost backup nose tackle D.J. Jones to a knee injury. Jones has been a key piece of the team’s rotation behind starter Earl Mitchell. The defensive line was the bright spot of the 49ers’ afternoon in Philadelphia. Leger Douzable had a pair of sacks while holding the Eagles defense to fewer than 4.0 yards per play for most of the afternoon.

Starting tackles Joe Staley and Garry Gilliam left the game in the first half with eye and leg injuries, respectively, and were ruled out.