Nationals outfielder Michael A. Taylor hit an inside-the-park grand slam to give the Nationals a 6-4 lead over the Phillies.
The play was made possible by the Phillies' Odubel Herrera, who badly misjudged a line drive to centerfield. After the ball flew over his head, Herrera jogged to retrieve the baseball rather than sprinting to ameliorate his mistake.
The homer was Taylor's 15th of the season, a career-high for the 26-year old.
Ironically, the last inside-the-park grand slam happened in September 2015, when Aaron Altherr hit one aided by a misplayed ball in centerfield by none other than Michael A. Taylor.
The rare Slam comes just one day after Taylor took a home run away from the Phillies' Andrew Blanco to help Washington win 4-3.