SAN FRANCISCO -- Carlos Correa’s megadeal with the Giants appears to have fallen through, as the All-Star shortstop agreed to a 12-year, $315 million contract with the Mets late Tuesday night, a source told MLB.com's Anthony DiComo.

The development was first reported by MLB Network insider Jon Heyman. The Mets have not confirmed the agreement.

It’s a stunning turn of events for the Giants, whose 13-year, $350 million deal with Correa never became official due to a disagreement over the prized free agent’s physical. The Giants had been planning to introduce Correa during a press conference at Oracle Park at 11 a.m. PT on Tuesday, but the team hastily postponed the event three hours before it was scheduled to take place.

Scott Boras, Correa’s agent, told reporters in New York on Thursday that president of baseball operations Farhan Zaidi called him around 8 a.m. PT on Tuesday to let him know about the abrupt change of plans. Correa was preparing to head to the press conference with his wife, parents, brother and in-laws when he found out about the postponement.

“[Zaidi] reported to me that they needed more time, more evaluation,” Boras said. “They had not made any decisions, but they weren’t prepared to go ahead with a news conference because they didn’t feel they would be able to collect the information within that short period of time.

“I said, ‘How much time do you need?’ They set the time, they told me 1 o’clock they would let us know. Then we received notice from them that they wanted to continue to talk and that they needed more time. But at that point in time, I told them I had to have a decision whether they were going to honor their letter of agreement that we had reached. And they said at that point in time they needed more information, they needed more discussion. They wanted to continue to talk, but at this time they couldn’t go forward. And then I advised them that I had to pursue alternative measures on behalf of Carlos with other teams.”

The holdup created an opening for the Mets to swoop in and consummate a new deal with Correa, who is now expected to slide over to third base and join fellow Puerto Rican star Francisco Lindor on the left side of New York’s infield.

The Giants have not publicly commented on the situation beyond this two-sentence statement issued by Zaidi on Wednesday: "While we are prohibited from disclosing confidential medical information, as Scott Boras stated publicly, there was a difference of opinion over the results of Carlos’ physical examination. We wish Carlos the best."

It’s unclear what specific medical issue the Giants flagged, but Boras said he did not expect any stumbling blocks to arise during Correa’s physical examination with the Mets on Thursday. 

“There is nothing with him that is currently any sort of medical issue,” Boras said. 

Correa, 28, dealt with back issues earlier in his career, but he’s averaged 142 games in the past two seasons, with his Twins tenure only interrupted by two occurrences -- a bout of COVID-19 and a bruised finger sustained on a hit-by-pitch. He underwent arthroscopic surgery to repair a fractured right fibula as a 19-year-old Minor Leaguer with the Astros in 2014, but he hasn’t spent any time on the injured list for a lower right leg issue since reaching the Majors.

Correa’s injury history should have been well known to the Giants, who hired longtime Astros executive Pete Putila as their new general manager on Oct. 11.

The Giants have now lost their top two free-agent targets to New York; they tried hard for Aaron Judge before he agreed to re-sign with the Yankees on a nine-year, $360 million deal. It’s unclear where they’ll pivot to now, because most of the top free agents are off the board at this stage in the offseason.