Andy Pettitte is scheduled to announce his retirement Friday afternoon The Post has learned.

Thus two members of the Yankees’ Core Four – Mariano Rivera and Pettitte – will be retiring after this season. Pettitte 41 has retired once already not playing in the 2011 season before returning to the Yankees in 2012.

However Pettitte has told friends this season has been very hard on his body physically much tougher than he had anticipated. The lefty also could see a great Yankees era coming to an end an era he was a major contributor in constructing.

Pettitte is 10-10 this year with a 3.93 ERA. He is scheduled to start Sunday against the Giants meaning his final home outing would coincide with Mariano Rivera Day at the Stadium. It also would line him up to make the final start of his career either Friday or Saturday back home in Houston.

Pettitte will release a statement this afternoon before addressing reporters later in the day at Yankee Stadium.