Early on Sunday morning, The Post has learned that the Mets and free agent left-hander Sean Manaea came to an agreement on a two-year, $28 million contract.

The agreement allows for a player opt-out following the 2024 campaign.

The addition of Manaea will strengthen a rotation that was already quite thin going into the winter after last year’s deadline deals that sent Justin Verlander and Max Scherzer, two potential Hall of Famers, to prospects.

The Mets earlier signed former Yankee Luis Severino for $13 million and traded Adrian Houser to the Brewers.

Right-hander Kodai Senga leads a rotation that also includes righties Severino and Houser. The southpaw Manaea helps balance the lineup.

The other left-hander who is certain to be in the rotation among lefties is Jose Quintana. Joey Lucchesi and David Peterson are still contenders to start.

Two other lefties, Hyun-Jin Ryu and Shota Imanaga, are free agents that the Mets have contacted. It’s possible that the Mets will add to their rotation, but it’s unclear if they are still considering those two pitchers.

The addition of center fielder Harrison Bader is one of the recent moves that should give the Mets, who have stated that they expect to be competitive in 2024, a chance.

Their rotation appears more reliable now that they have strengthened their up-the-middle defense, even though it is not nearly as star-studded as it was at the start of the 2023 campaign.

The veteran Manaea, 31, posted a strong finish in the Giants rotation last year, going 2-1 with a 2.67 ERA in September while making four starts and one relief appearance.

Manaea had been used mostly in relief after a rough start in April, when he posted a 7.85 ERA. Overall, he was 7-6 with a 4.44 ERA last year.