UPDATE, 5:05 p.m.: As noted below, Buster Posey was scratched from the lineup against the Red Sox. He did not start in St. Louis on Sunday either and revealed he has been dealing with a nerve irritation in his right thumb for a while. He has been able to play through it but said, “It’s a little more flared up” and he feels it more when he makes weak contact.

Manager Bruce Bochy said Posey might sit Wednesday night, too. With an off day Thursday he would have a total of five days without playing to calm the nerve.

Posey could not say whether the injury has affected his hitting. When Bochy was asked he initially said, “No question,” but then offered a clarification. Bochy said Posey’s line-drive rate ranks among the highest in the majors, but the thumb injury could be affecting Posey’s power.

Posey is slugging .450, down 20 points from last year and 40 points from the year before. He has eight home runs and an un-Posey-like .257 batitng average.

Meanwhile, Madison Bumgarner and Bochy addressed a story that has blown up the past three days.

Bumgarner told Buster Olney of ESPN on Sunday that he would like to participate in the All-Star Game Home Run Derby. The story gained more traction when ESPN broadcast Bumgarner’s batting practice from St. Louis, when he blasted homer after homer into the second deck at Busch Stadium, and even one into the third deck.

The league has not actually asked Bumgarner to participate, but Bochy said he will discuss the issue with the left-hander and general manager Bobby Evans. The issue is the Giants’ rotation ace risking his health in a hitting exhibition.

“Your initial feelings are to keep him out of it because of how competitive he is and how hard he’d swing,” Bochy said. “But it would create great interest for the fans to see one of the best pitchers in the game swing the bat.

“That’s a lot of swings. I’m not worried about him losing his swing as much as going out and take that many swings and maybe hurting an oblique.”

Bumgarner wanted to make three things clear: One, he would be honored to participate. Two, he thinks he would do well, but three, he has not politicked to be included. He stressed that the issue arose when he was asked if he would like to be in the derby.

Bumgarner did scoff at the injury risk in a very colorful way.

“They had me ride a horse on the field,” he said. “If they trust me with something like that with 40,000 people going crazy and I can’t do a baseball activity, that would be a little different.”

ORIGINAL POST: The Giants had a lineup card with Buster Posey catching. Now, it’s been revised without him. We’ll find out why when the clubhouse opens shortly.

Now, the Giants must face Rick Porcello and baseball’s most potent offense, the Red Sox’s, without their cleanup hitter. Both lineups are below.

*****

It’s hard enough to keep track of the organization you cover, much less a different organization in another league. So I’m not really sure why the Angels gave up on Albert Suarez after he won the Texas League ERA last year.

Granted, at 25 he was a little old to be pitching in the Texas League, suggesting a slow development, and the Angels might have felt they needed the 40-man spot for better prospects. But still, there is not another major-league team more starved for starters than the Angels.

It’s June 7 and they already have had eight different pitchers start at least one game, but Tim Lincecum to go.

The Angels’ loss is the Giants gain. Suarez seems perfectly suited for the Yusmeiro Petit role, and we all know how crucial it is.

He throws 94 mph, has four pitches and looks fearless. Manager Bruce Bochy had him pitch the ninth inning of a 2-0 game the Giants were losing for his big-league debut, then had him pitch in the 13th inning against the Blue Jays. Suarez got into and out of trouble and got the win.

Then, he pitched five bullpen-saving inning after Matt Cain injured his hamstring in Colorado at the start of the last trip, and took a one-hitter into the sixth-inning of his first big-league start at Atlanta last week.

Tuesday night’s test will be tougher, of course. Suarez will face the majors’ most potent offense in the first of two games against the Red Sox. He will have to be on his game.

David Ortiz is not expected to play first base. Nick Cafardo of the Boston Globe tells me Ortiz has been nursing a sore foot after he was hit by an R.A. Dickey pitch a few days back.

As I mentioned in game story from Sunday, this is a big homestand for the Giants. They play two against Boston, three against the Dodgers and three against the Brewers, and will learn just how challenged they will be without Hunter Pence.

After Sunday’s loss, Jake Peavy had an interesting and unusual comment. He implored the fans to come out and really support the Giants at AT&T. They usually do, but maybe he had in mind how well the Red Sox fans travel and how they can take over a quiet stadium, the way Giants fans do in San Diego

Lineups:

RED SOX

Betts RF

Pedroia 2B

Bogaerts SS

Shaw 3B

Ramirez 1B

Bradley Jr. CF

Young LF

Vazquez C

Porcello P

GIANTS

Span CF

Panik 2B

Duffy 3B

Belt 1B

Crawford SS

Blanco RF

Parker LF

Brown C

Suarez P

Henry Schulman is a San Francisco Chronicle staff writer. Email: hschulman@sfchronicle.com