"I don't think it's anything too crazy," Posey said. "It's something I've dealt with off and on."
Manager Bruce Bochy said that Posey will likely sit out Wednesday. With an off-day on Thursday, Posey could potentially get five consecutive days off to rest his injury.
"It may effect some power," Bochy said. "If that hand is not right, you're going to lose some power."
Posey is hitting .257 with eight homers and 26 RBIs this year. He was available to pinch-hit.
"It flared up on him from hitting," Bochy said. "That was a big reason why he was off that last day in St. Louis. It's better to give him a couple of days. It's still in there. There's a good chance he could miss tomorrow, too. Give him one, two, three, five days; letting it clear up."
Trevor Brown replaced Posey in the lineup.
Michael Wagaman is a contributor to MLB.com and covered the Giants on Tuesday. This story was not subject to the approval of Major League Baseball or its clubs.