ST. LOUIS -- Giants manager Bruce Bochy remained uncertain Thursday about right-hander Matt Cain's availability for Saturday's start against the St. Louis Cardinals.
Cain strained his right hamstring May 22 at Colorado and has not pitched since. Thursday, he played catch with left-hander Madison Bumgarner as head athletic trainer Dave Groeschner watched closely.
Bochy said that he and the team's medical staff want to see how Cain feels Friday before determining whether he'll pitch the next day. Hamstring injuries can linger stubbornly, accounting for the Giants' cautious approach with Cain.
San Francisco's No. 2 starter, Cain is 1-3 with a 3.66 ERA in eight starts. He went on the disabled list last month with a cut on his right index finger, which forced him to miss two starts.
Yusmeiro Petit likely would start Saturday if Cain isn't physically ready.
Recurrence of back issue sidelines Posey
ST. LOUIS -- Back problems struck Buster Posey for the second week in a row, preventing the Giants catcher from starting Thursday night's series opener against the St. Louis Cardinals.
Nerve irritation in Posey's lower back forced him to miss games against the Colorado Rockies on May 20 and 21. He insisted the flight to St. Louis did not aggravate his discomfort.
"It's nothing crazy," Posey said. "It's just off a little bit."
He said he felt "pretty back to normal" between the time his previous episode subsided and Thursday.
Posey, who's in a 3-for-34 skid that has lowered his batting average to .254, declared himself available to pinch-hit.
Giants manager Bruce Bochy indicated that he didn't consider Posey's injury serious and rejected the notion that this could be a recurring health issue. But Bochy wants to guarantee that Posey's ailment doesn't become chronic.
"We'd like to get this thing taken care of," Bochy said.
Hector Sanchez replaced Posey, starting his 18th game behind the plate.
Lincecum not worried about finger blister
ST. LOUIS -- Giants right-hander Tim Lincecum seemed unconcerned about the blister on his right middle finger that forced him to leave Wednesday's game against the Chicago Cubs with a no-hitter through five innings.
Lincecum said he expected to start Tuesday's series opener at Cincinnati. He pointed out that Monday's scheduled off-day will help him recover more fully before he takes his next turn on the mound.
Lincecum was taking a gentle approach toward treating his finger.
"I'm just letting it naturally dry out," he said, eschewing substances, such as pickle juice, that pitchers frequently apply to their fingers to treat blisters.