(Mark J. Terrill/AP)

LaRoche has not recently dealt with any oblique issue, but he has battled constant injuries since he signed a two-year contract with the Nationals last winter. LaRoche missed the final 4 ½ months of last season after undergoing surgery to repair the labrum in his left shoulder. This spring, LaRoche recovered from a bone bruise on his left foot.

If LaRoche has only soreness in his oblique, he may recover in a matter of days. But if the soreness is symptomatic of a strain, LaRoche could miss at least two to three weeks, likely more.

In the Nationals’ new lineup, Jayson Werth will bat cleanup and Chad Tracy will bat fifth and play first base. Here’s the full lineup:

1. Ian Desmond, SS

2. Steve Lombardozzi, 3B

3. Bryce Harper, LF

4. Jayson Werth, RF

5. Chad Tracy, 1B

6. Danny Espinosa, 2B

7. Rick Ankiel, CF

8. Wilson Ramos, C

9. Ross Detwiler, SP