Eight games into the 2012 season, the Giants have suffered a potentially devastating injury. Closer Brian Wilson is facing likely elbow surgery and might be lost for the season.

An MRI on Friday night revealed that Wilson has “structural issues” with the ligament in his right elbow, manager Bruce Bochy said Saturday before the Giants’ 4-3 victory over the Pittsburgh Pirates at AT&T Park. Wilson has been placed on the 15-day disabled list, but he’s probably going to be out a lot longer.

After a 32-pitch inning against Colorado on Thursday in which he struggled to get the save during a 4-2 Giants’ win, Wilson complained of elbow stiffness Friday. Subsequent tests revealed structural damage, to what degree the club was not yet prepared to say.

Bochy and trainer Dave Groeschner said Wilson would be examined by team orthopedist Dr. Ken Akizuki and that calls then would be made to set up second and third opinions, including from noted Pensacola, Fla., elbow surgeon Dr. James Andrews, before making a final determination about surgery.

The manager did not sound optimistic.

“After the tests (Friday), it doesn’t look very good right now,” Bochy said. “He’ll get a couple more opinions, but he’s likely facing surgery, to be honest.”

There have been questions about Wilson’s health since he blew a save in a 5-4 walk-off loss to Atlanta on Aug. 15. Wilson was examined by Andrews two days later and placed on the disabled list Aug.

21 with inflammation in the elbow. He was reinstated Sept. 18 but appeared in just two games before being shut down for the remainder of the season.

During spring training, Wilson said the late-season shutdown was done for precautionary reasons and that there were no issues with the elbow.

“I am healthy, and I’m doing everything I can to make sure everyone is aware of that,” he said March 26. “(The elbow) wasn’t a concern for me.”

Wilson, who turned 30 last month, made six appearances in spring training, throwing 51/3 innings with no earned runs allowed, two walks and eight strikeouts.

He made his regular-season debut Wednesday, pitching the eighth inning of a 17-8 loss in Denver. He gave up a run on one hit and one walk, throwing 24 pitches.

Wilson’s second outing of the season was even more difficult. He loaded the bases and walked in a run before preserving a 4-2 victory. At one point, Bochy and Groeschner, along with catcher Buster Posey, came out to check on Wilson. He took a warm-up pitch and finished the game, and afterward, Bochy said Wilson had tweaked his left ankle. His velocity declined noticeably during the inning.

Groeschner said the elbow issue became apparent Friday afternoon when Wilson went through his pregame routine.

“Even though he was off, he still had to throw and prepare,” the trainer said. “That’s when he came and talked to us.”

Said Bochy: “I feel for Willie. He’s worked hard with rehab, and he’d come a long way. We checked off every box with him, back-to-back days, everything. I think he was all set to go, and then this happens, so it’s a disappointing day for Willie personally, and then obviously the team.”

Wilson was not available for comment, but Bochy spoke with him.

“I’m sure he’s disappointed with what’s happened, and we all feel terrible,” the manager said. “But he said, ‘Hey, I’ll be back to help you guys.’ “

If Wilson requires Tommy John ligament replacement surgery, however, his season will almost surely be over. It would be his second such surgery — he had the procedure in 2003 while attending LSU. The Giants nonetheless drafted him in the 24th round that year.

Wilson has 171 career saves, including 36 last season. He led the majors with 48 saves in 2010 and had six more in the postseason, including closing out all three series-clinching wins en route to the Giants’ first World Series victory in San Francisco.

Bochy said Ryan Vogelsong, who was scheduled to come off the disabled list Sunday to make his first start of the season, would replace Wilson on the roster.

As for how Wilson would be replaced in the bullpen, Bochy said it would be a closer by committee for the time being.

“It’ll be similar to last year when Willie was out,” he said. “We’ll use everybody, go with the hot hand. (Santiago) Casilla may be saving some games. (Sergio) Romo and (Javier) Lopez, we think we’re in good hands there. That’s the game plan right now.”

Wilson could be joining a long list of pitchers throughout baseball who have suffered elbow injuries early in the season. Cincinnati closer Ryan Madson underwent Tommy John surgery earlier this week, as did the A’s Joey Devine and the Angels’ Michael Kohn.

Kansas City closer Joakim Soria had the surgery April 3, and Minnesota right-hander Scott Baker is scheduled for season-ending surgery to repair the flexor pronator tendon in his elbow. The Twins released right-hander Joel Zumaya after he injured his elbow in his first spring training bullpen session.