SAN FRANCISCO -- The Giants basically set their 25-man Opening Day roster Tuesday night following a rain-shortened, 4-2 loss to the Oakland A's. It's not likely to include outfielder Mac Williamson.

Once considered a promising power hitter, Williamson had a miserable spring, hitting .237 with one homer and five RBIs. He then had injury added to insult in the final exhibition game of the spring when he was struck on the right hand by A's pitcher Brian Schlitter, which required X-rays.

Manager Bruce Bochy said the X-rays were negative, then he also made it pretty obvious there would be no place for Williamson as he announced the 12 position players the Giants intend to keep for Thursday's opener against the Padres at Petco Park.

They include outfielders Michael Reed and Connor Joe, and infielder Pablo Sandoval.

Reed and Joe were both acquired in the past week from the Minnesota Twins and Cincinnati Reds, respectively. They'll likely receive a good amount of playing time in left. Steven Duggar will man center and Gerardo Parra should get most of the playing time in right.

Reed can play all three outfields and has impressed the Giants with his defense during his short time in San Francisco. Joe gives the club versatility because he can play left, first base and catch.

Sandoval will be a reserve infielder along with Yangervis Solarte, backing up regulars Brandon Belt, Joe Panik, Brandon Crawford and Evan Longoria.

"You look at the job he did last year," Bochy said of Sandoval, who hit .248 with nine homers and 40 RBIs in 92 games. "He gives us a good bat off the bench and versatility."

Erik Kratz will be Buster Posey's caddie behind the plate.

That's 12 position players and no room for Williamson. The Giants will have to decide whether to trade him, designate him for assignment or cut him since he's out of options. They could put him on the injured list with a bruised hand while they decide what to do.

Bochy seemed most distressed about having to let infielder Alen Hanson go. The manager said the Giants will do everything possible to find him another club.

"The tough part was telling Alen Hanson," Bochy said. "He plays so hard, but there wasn't a spot for him."

Setting the rotation

After Madison Bumgarner pitches the opener Thursday in San Diego, he will be followed in the rotation by Derek Holland, Dereck Rodriguez, Jeff Samardzija and Drew Pomeranz.

Samardzija and Pomeranz worked in Tuesday's contest. Samardzija pitched 3 2/3 innings and was roughed up for six hits and four runs. He was taken deep by A's outfielder Mark Canha in the fourth.

"The last start of the spring is always a tough one," said Samardzija, who posted a 1-1 record and 3.97 ERA in 22 2/3 innings. "I was behind in the count and had to attack the zone a lot. But I'm trending in the right direction."

Pomeranz was superb in his two innings, allowing one hit, walking one and recording five strikeouts.

More roster decisions

Bochy said left-hander Travis Bergen and right-hander Trevor Gott will be part of an eight-man relief staff. The addition of Bergen gives Bochy three lefties in his bullpen, including Will Smith and Tony Watson.

The Giants still haven't picked a closer. It's expected to be Smith, who's unscored upon in six innings. Watson could be a contender with a 1.50 ERA, also in six innings.

In addition to Gott, the righties in the bullpen are Sam Dyson, Mark Melancon, Reyes Moronta and Nick Vincent.

Solarte in the outfield

Expect to see Solarte in left field on occasion, especially when a right-hander starts against the Giants.

Solarte hasn't played in the outfield during the regular season since 2014, when he appeared in seven games in left for the Padres.

"I'll play wherever they need me," Solarte said before Tuesday night's exhibition.

Solarte isn't going to win a Gold Glove, but if he can handle the position respectably, he could provide some pop to the Giants lineup. He hit just .226 last season for the Blue Jays, but his 17 homers in 122 games were more than any Giant hit last year.

Solarte had a little trouble on a fly ball to left in the second inning off the bat of Mark Canha, allowing it to fall for an RBI double and the first run of the game. But two batters later, he made an over-the-shoulder, leaping catch on what turned into a sacrifice fly by former Giants catcher Nick Hundley.