SAN FRANCISCO -- Buster Posey was doing well after being struck in the helmet in the first inning of San Francisco's 4-1 home-opening win Monday.

He was examined for a concussion after being hit by a 94 mph fastball from Arizona starter Taijuan Walker.

Posey will be re-evaluated Tuesday, but manager Bruce Bochy said, "He's doing good, he's doing fine."

Posey was struck by an 0-1 pitch with two out in the first and immediately went down.

Athletic trainer Dave Groeschner sprinted toward the plate and Bochy was right behind. Posey got up on his own but exited the game, with Nick Hundley entering to pinch run and stay in the game as catcher.

Walker was booed at the conclusion of the inning and every time out thereafter.