(Julio Cortez/AP)

“He must be feeling pretty good, because he wanted to know if he could off some live arms over on the other field,” Johnson said. “I think he’s feeling pretty good. We’re just being on the cautious side.”

While LaRoche watches, Stephen Strasburg well make his first start of the spring on a gray, cool day. (Good preparation for an opening day start in Chicago, perhaps? “I’ll be watching him close,” Johnson said, smiling.) Strasburg will throw a maximum of 45 pitches in either two or three innings, depending on how it goes.

Bryce Harper is not today’s lineup, but he is listed as a late-inning replacement in right field. He’s in tomorrow’s lineup against the Mets, a night game in Port St. Lucie, batting sixth and playing right field.

Today’s game, which starts at 1 p.m., will be broadcast live on MASN. You can also listen to it on the radio on 106.7. It rained hard this morning, but the rain has subsided and is expected to stay away for the remainder of the afternoon.

Here are the next two Nationals’ lineups, today and tomorrow.

Today’s lineup, vs. Astros

1. Ian Desmond, SS

2. Danny Espinosa, 2B

3. Ryan Zimmerman, 3B

4. Michael Morse, DH

5. Jayson Werth, CF

6. Mark DeRosa, 1B

7. Wilson Ramos, C

8. Jason Michaels, LF

9. Brett Carroll, RF

-Stephen Strasburg, SP

Behind Strasburg, the Nationals have some of their best relievers throwing. The schedule goes Tom Gorzelanny, Drew Storen, Ryan Mattheus, Tyler Clippard and Brad Lidge.

Monday’s lineup, at Mets

1. Roger Bernadina, LF

2. Steve Lombardozzi, 2B

3. Mark Teahen, 3B

4. Chad Tracy, 1B

5. Rick Ankiel, CF

6. Bryce Harper, RF

7. Jesus Flores, C

8. Xavier Paul, DH

9. Andres Blanco, SS

- John Lannan, SP

The relievers: Sean Burnett, Atahualpa Severino, Waldis Joaquin, Rafael Martin, Ryan Perry, Craig Stammen

Also, Chien-Ming Wang will pitch in a simulated game tomorrow against minor league batters.