CLEARWATER, Fla. — Jorge Posada took a stab at playing first base for the Yankees against the Phillies on Thursday at Bright House Field.

“It was very different,’’ Posada said of a position he has played in 28 big-league games (15 starts; none since 2008). “It’s a process, especially with guys on base and double plays. It doesn’t come instinctively to me. I have to think about it beforehand. I am like a fish out of water.’’

If Eric Chavez stays healthy, he is likely to be Mark Teixeira’s primary back up at first base. However, there is a chance Joe Girardi could use switch-hitting Posada.

“To give Tex a day off here and there,’’ Posada said. “He is the best first baseman in the league.’’

Posada handled 12 chances without a mistake and speared Placido Polanco’s first-inning liner out of the air to start a double play in a game the Phillies won, 7-0.

“Self defense, it was right at me,’’ Posada said.

Posada said he has embraced the shift from catcher to DH.

“I am clear with what is going on, I understand what’s going on,’’ Posada said. “I am looking forward to DH’ing and having a good year.’’

Girardi said, “We will see how it goes. He worked out there for a couple of days. We don’t know the makeup of our team yet. We might put Jorge at first to get his bat in the lineup.’’

Posada’s surgically repaired left knee didn’t allow him to participate in catching drills during the early days of camp. Now, it isn’t limiting Posada.

“The knee hasn’t been a hindrance at all,’’ Girardi said.