With one swing of a non-existent bat, Washington Nationals outfielder Michael Morse put his team ahead 4-0 - and provided one of the greatest highlights of the Major League Baseball season.
Morse came up with the bases loaded in the top of the first inning and drilled a pitch from Cardinals right-hander Kyle Lohse barely over the right-field wall. The ball caromed off an advertising sign and bounced back onto the field, causing plenty of confusion.
The play was originally ruled a run-scoring single, and Morse was picked off after unsuccessfully trying to scramble back to first base as the throw beat him there. Morse couldn't believe the play wasn't ruled a homer - and as it turned out, he had a really strong case.
What follows has to be seen to be believed.
Umpires confer at the end of the play as Nationals manager Davey Johnson prepares to argue the ruling that the ball remained in play. After a two-minute video review, the umpires determined that the ball did, in fact, clear the wall, giving Morse his second career grand slam.
But it wasn't as simple as having him trot around the field. Umpires had to return each runner to his respective base as Morse performed the ol' reverse jog around the bases before ending up at home plate again.
With his bat already tucked back in the dugout by the bat boy, Morse simply swung his invisible bat at the invisible ball, then watched it sail invisibly over the right-field wall before beginning his real home-run trot.
Washington went on to win the game 6-4.