But less than a half an hour after that lineup was posted, a new lineup was set with Harper scratched and Michael A. Taylor inserted to play center field and bat seventh.
"We thought he was going to be OK," said Nationals manager Davey Martinez. "He's out there trying to get loose this morning and it just wouldn't get loose. Pretty swollen still, so. Rather than him try to play through it, we thought the best option would be have him come off the bench if we need him and hopefully throughout the day he'll get loose. He's going to stay in and get treatment ready most of the day. Hopefully get him ready to pinch-hit."
Martinez said the second time Harper was hit by a baseball in the last few days was lower than the first time, ranging between the kneecap and his shin.
"It's underneath his knee, sort of like on his shin but he couldn't flex his ankle or anything," Martinez said. "It's pretty sore. That's twice in a week. Little lower, same vicinity. He has one little bruise up here and another like (further down). It's pretty swollen."
Martinez said the X-Ray results on the knee and shin came back negative.
"It will be day-by-day but he told me if we need him he should be available later on," the skipper said.
* Martinez said right-hander Stephen Strasburg's side session went well and he envisions a rehab assignment in the near future.
"Good, said he felt good," Martinez said. "He's scheduled to throw another one in a couple days and we'll see what happens after that.
"He's probably going to need a rehab assignment. We'll determine that after he throws the next bullpen."
* Martinez acknowledged that umpires sometimes make mistakes in ball-strike calls but also said that rookie outfielder Juan Soto could have handled the situation better when dealing with home plate umpire Greg Gibson.
"Absolutely, this is a discussion I will have with him sometime today or maybe even tonight on the plane about just, hey, nobody's perfect," Martinez explained. "Those guys go out there and they got a job to do and for the most part they're pretty good at it. They really are. So, you know what? Take it with a grain of salt and go out there and compete. You always tell me all you want to do is play baseball? Just concentrate on playing baseball. I know it's frustrating sometimes, but it's part of the game."
* Right-hander Joe Ross, rehabbing from Tommy John surgery, started three innings for rookie-level Gulf Coast League Nationals against the Astros on Monday. He did well, throwing three shutout innings, allowing no hits and striking out five, walking two.
"I heard he threw well," Martinez reported. "He's still got some time. But I heard he threw well and he's progressing every day. And he looked good."
With Ross just starting rehab games, does Davey think he could have a shot to contribute to the Nats before the season ends?
"I think he is somebody that if he continues to do what he's doing, yeah, absolutely," Martinez said. "But he'll have to keep progressing."
Martinez said he is open to using Ross out of the bullpen but he could also return to his role as a starter "later on".