Rodriguez tweaked his strained oblique muscle taking batting practice Wednesday in Houston, Johnson said. The Nationals are concerned Rodriguez would be at risk of tearing his oblique if tried to comeback.

“Pudge is not doing too good,” Johnson said.

Rodriguez was present in the Nationals clubhouse before today’s game, but he will leave the team to head to Miami, where he will work out with a longtime personal trainer who also works for the Miami Heat.

“I’m not 100 percent right now,” Rodriguez said. “It’s still right there. If you’re still hurt, it’s not 100 percent. That’s what it is. That area, I asked guys that have that before. It takes some time. It’s one of those pain-in-the-butt injuries.”

After Rodriguez finishes his therapy, the Nationals will re-evaluate. Rodriguez, who last played July 6, will then have to regain his timing with the Nationals’ Gulf Coast League affiliate.

The missed time will stunt Rodriguez’s chase to become the first catcher with 3,000 career hits. Rodriguez, 39, needs 158 more hits to reach the milestone, and sitting out with the injury will cost him precious at-bats. This season, Rodriguez has added 25 hits in 117 at-bats.

Without Rodriguez, Jesus Flores will become the Nationals’ backup catcher, playing every third game, Johnson said. Flores returned this spring after missing most of 2009 and all of 2010 while recovering from a torn labrum. Flores is 3 for 15 with no walks and a double in limited time this season in Washington.

Defensively, Flores’s throwing still seems to be affected from his shoulder injury. Johnson is optimistic that less playing time will allow Flores, who had played frequently at Class AAA Syracuse, to build up his arm strength. Today, Flores worked on throws from home to second with bench coach Pat Corrales.

“He’s not throwing like he did a couple years ago before he hurt his shoulder,” Johnson said. “But he’s got a good, quick release, gets it down there in a hurry.”