SAN FRANCISCO — Already banged up, the Giants took another blow early in Friday’s series opener against the Reds.

Giving chase to a fly ball in the top of the first, Austin Slater crashed in the center field fence and an inning later was lifted for a pinch-hitter.

Slater left the game with concussion-like symptoms, the Giants later announced.

He was slow to get up from his encounter with the outfield wall and was shown walking down the dugout steps and into the clubhouse accompanied by head trainer Dave Groeschner.

With left-hander Andrew Abbott on the mound for Cincinnati, Slater received his customary start while holding the platoon advantage but was only in center field because Jung Hoo Lee was already day-to-day with a bruised foot. Set to face another lefty, Nick Lodolo, on Saturday, the Giants were already missing two of their right-handed bats in catcher Tom Murphy (knee) and designated hitter Jorge Soler (shoulder).

Slater collided full-speed with the chainlink portion of the outfield fence in front of the Giants bullpen while the ball off Spencer Steer’s bat fell to the ground. Already on second base after a single and a steal, Elly De La Cruz scored to give the Reds a 1-0 lead in the top of the first.

Michael Conforto entered for Slater, and Tyler Fitzgerald shifted from left to center field.

In limited playing time entering Friday, Slater had five hits — none for extra bases — in 48 plate appearances this season, a .132 batting average and .444 OPS.