In the fourth inning, with the score tied at 2 and Matt Wieters on first base, Orioles center fielder Adam Jones took an 0-1 pitch to deep center field. Morgan jumped as the ball hit the wall, but as he missed the catch, Morgan thought the ball was gone and threw his glove to the ground out of frustration.
Left fielder Josh Willingham ran over and retrieved the ball, but by the time it reached home plate, both Wieters and Jones scored to give Baltimore a 4-2 lead, and Jones was awarded an inside-the-park home run.
"Morgan missed the ball, and I saw it get away from him, and I saw him mad." Jones said. "He threw his glove down, and I kept running. [Third-base coach] Juan [Samuel] just never stopped me, so I kept on running."
Said Willingham, "It was pretty helpless in my situation. I saw the ball hit the ground. I was pointing and yelling. Nyjer couldn't see me nor couldn't hear me. I just continued to run and picked it up."
It was the second inside-the-park home run at Nationals Park this week. On Wednesday, Mets center fielder Angel Pagan accomplished the feat after the ball went over Morgan's head and angled off the wall into left field.
At first, Nationals manager Jim Riggleman wanted to take Morgan out of the game on Saturday, but then he realized that Morgan thought that Jones' ball went over the fence. So the skipper decided to keep Morgan in the ballgame.
It helped that before the inning was over, Riggleman had plenty of time to think about what Morgan had done. Riggleman also realized the team couldn't afford to take Morgan out of the game because catcher Ivan Rodriguez left the game after three innings because of a lower back strain.
"My first instinct was to take him out of the ballgame," Riggleman said about Morgan. "And then I said, 'You know what? He thinks that ball went over the fence. He thought he knocked it over the fence and it's a home run.' That's not an excuse for it, and I don't want it to be perceived as an excuse, but it explains it.
"So he made a human error. It was a horrible thing, he made a terrible mistake, but it wasn't malicious. It wasn't directed at anything other than he was mad that he didn't catch the ball, and he thought he knocked it over the fence."
Morgan didn't have any excuses after the game. He indicated that he let his emotions get the best of him.
"I went back for the ball, I leaped up and thought the ball went over the fence," Morgan said. "I guess it didn't, and it was standing right there. I really didn't check out the inside-the-park homer. My emotions got to me, because I knew I should have had the ball."
Nationals closer Matt Capps has known Morgan for eight years dating back to their Minor League days with the Pirates. Morgan is known as an emotional player, but he is always aggressive on the field.
"That what makes him so good," Capps said. "Obviously, you don't want to see the results the way it was, but that fire that he plays with, he has to have that to be successful. I'm the last person to tell him how to change. Obviously, I wished he would have looked around first. Nobody in the ballpark felt worse about that than Nyjer Morgan "
As he was going off the field, Morgan heard a lot of boos from the 30,290 fans at the park. However, Morgan stepped into the batter's box in the bottom of the fourth and singled to right field off Brad Bergesen.
"The fans had every opportunity to boo me," Morgan said. "The Nats Nation definitely knows I'm a hard-working player and I'm going to leave it out there on the line."
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.