Alex Rodriguez: 'This Is a Tough Day' ... I'm Retiring

A-Rod barely held back tears as he announced his retirement from professional baseball.

The 41-year-old star held an emergency press conference Sunday morning at Yankee Stadium ... saying he didn't want to leave the active roster, but after conversations with honcho Hal Steinbrenner, is "at peace" with the transition.

The Yankees said A-Rod will play his last game Friday in the Bronx ... and then serve as a special adviser for the organization through the remainder of his contract next year.

He's still owed $27 million ... but his GF is worth billions ... so he'll be ok.

#ARODAARP