Alex Rodriguez tied Willie Mays for fourth on baseball's career home run list by hitting No. 660 on Friday night.
A-Rod smacked a 3-and-0 pitch from Boston's Junichi Tazawa over the Monster at Fenway Park in the eighth inning for the historic home run.
It is the sixth home run of the season for the Yankees' DH/corner infielder and his 53rd against the Red Sox.
Whether it is a "milestone" that would deliver $6 million of the Yankees' money to Rodriguez based on his contract's incentive clauses remains to be seen.
The Yankees told Rodriguez in February they do not plan to pay him that money because, from their perspective, it's no longer a marketable milestone given his year-long suspension in 2014 for his involvement with performance-enhancing drugs and the Biogenesis scandal.