"It is July, and we do have four catchers," Acta said. "We have to make some decisions, so we'll take a look at Johnny."
Estrada was reinstated from the 15-day disabled list and recalled from Double-A Harrisburg on Friday, a day after left fielder Wily Mo Pena announced that he will have surgery to repair a small tear and impingement in his left rotator cuff, a procedure that could keep him out the rest of the season.
Estrada, who signed a one-year deal with the Nationals during the offseason, had a bone spur removed from his right elbow in October and has never fully recovered.
Since that surgery, he has been bothered by recurring tendinitis and has played in only 17 games this season, none since April 30. He had seven hits in 39 at-bats this season for the Nationals before beginning a 16-game Minor League rehab assignment on July 2.
"I still get some pain, but I don't think that's going to go away until I can get a long period of rest," said Estrada, who batted seventh during Friday's series opener against the Braves, his former team.
Although he still feels occasional discomfort and stiffness in his elbow, Estrada said he was more concerned with regaining the strength in his arm. Those worries were eased last week when he threw out a speedy runner during a rehab game.
"I saw a flash of my old arm," he said.
And it was enough to convince Estrada that he will be able to make an immediate impact for Washington. If he can't, the Nationals still have three other catchers -- Paul Lo Duca, Wil Nieves and Jesus Flores -- on the active roster.
Lo Duca started at first base on Friday night. He can also play left field, which he has played three times this season.
"We are blessed to have a bunch of guys who are very versatile," Acta said. "We're covered when it comes to the position players."
Ryan Lavner is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.