Aaron Judge broke Mark McGwire's rookie record by hitting his 50th home run of the season in the bottom of the seventh against the Royals.
Judge hit his 49th earlier in the game.
Judge's 50 homers are the ninth-most in Yankees history, passing Lou Gehrig's total of 49 1934 and 1936 seasons and Babe Ruth's 1930 campaign.
After hitting 31 home runs before the All-Star break, Judge fell into a significant slump and entered September with 37 homers. At that point, it seemed highly unlikely that he would even challenge McGwire's record, which was set in 1987, let alone break it.
But Judge found his groove once again and has now hit 13 home runs in September. As an aside, Judge is the only player in MLB history to hit 50 home runs and strike out 200 times in the same season.