Watch: A-Rod hits HR No. 661, passes Willie Mays for 4th on all-time list
The historic home run came during Thursday's game against the Baltimore Orioles at Yankee Stadium. On a 1–1 count, Rodriguez hit an 83 MPH changeup from Orioles righthander Chris Tillman to give the Yankees a 3–2 lead in the third inning.
It was Rodriguez's seventh home run of the season.
His 660th career home run likely set up a legal battle against the Yankees, as general manager Brian Cashman told ESPN the team does not plan to pay Rodriguez a $6 million bonus for tying Mays.
Rodriguez is believed to be owed five payments of $6 million for hitting a series of home run milestones as he climbs MLB's all-time list, the first of which was reached by hitting No. 660. Those bonuses are reportedly detailed in an addendum to the 10-year, $275 million contract Rodriguez signed with New York in 2007.
If the Yankees don't pay him his first bonus, Rodriguez will likely file a grievance with the MLB Players Association that will likely end up in arbitration, the New York Post previously reported.
Rodriguez, who turns 40 in July, was suspended for the entire 2014 season for his role in the Biogenesis scandal and use of performance-enhancing drugs.
- Molly Geary and Mike Fiammetta