(Lenny Ignelzi/AP)

Moore went 1 for 3 in the Nationals’ 2-0 loss and handled his lone play in left, a line drive to his right, with ease. The 25-year-old had hit 62 home runs in 2010 and 2011, second-most in minor league baseball, and smashed seven more this season. Now he’s got one single in the major leagues.

“It was a great day,” Moore said. “It was fun. It was everything I hoped it was going to be. Lotta people.”

The Nationals summoned Moore because Mark DeRosa landed on the disabled list with a strained oblique. But he would started his big league career off the bench if not for Werth’s sudden migraine.

Werth woke up Sunday feeling fine, but once he arrived at the park his head throbbed and light made him dizzy. He described his symptoms to a trainer, who informed Werth he had a migraine. Werth, as far as he remembered, had never had one before.

“It’s surprising,” Werth said. “I was fine when I woke up. As soon as I got here, I didn’t feel so hot.”

The searing pain kept him in the trainer’s room for the first seven innings. He dressed and went to the dugout, but “I still didn’t feel very good.” Even then, only an emergency would coax him into the game.

“The last thing I want to do right there is not be able to play,” Werth said. “I was pretty much trying everything we could do. I couldn’t overcome that. I’ve never had that before.”

And so Moore took his spot in left field. Before this year, Moore had played 414 games in the minor leagues, all of them at first base. This week, as the Nationals realized they may need an outfielder, Moore played three games at Class AAA Syracuse in left. That was the entirety of his outfield game experience before he took the field for his first major league game.

“Every time I go out there, I feel more comfortable,” Moore said. “As many reps as I can get, the better I feel, whether it be BP or in the game. Just trying to get as comfortable as I can and make the routine out there, not make a fool of myself.”

Moore caught a line drive, which he calmly read. But he feels most comfortable at the plate – “an unbelievable hitter,” Bryce Harper called his former Syracuse teammate. He crushed a foul ball to left in his first at-bat before grounding out. Then, in his second at-bat, Moore led off the fifth with a line-drive single to right-center field.

“It was good to knock it out of the way,” Moore said, “and worry about something else now.”