Lo Duca was hoping to be activated on Thursday, but general manager Jim Bowden said he wanted Lo Duca to get four more at-bats before coming back to the Major Leagues.
"I think it's important that Paul Lo Duca gets four more at-bats," Bowden said. "He and I talked last night. He hit the last couple balls really hard; almost hit a home run in his last at-bat. I just would feel better with four more at-bats down there. So, we're going to hold off on making a move until tomorrow."
With Lo Duca coming back, it means two things: Reliever Chad Cordero will be placed on the disabled list and the Nationals will carry three catchers.
Cordero is expected to miss four to six weeks because of a tear in his right shoulder adductor. No surgery is needed.
Cordero hurt the shoulder adductor in Tuesday's game against the Braves in the ninth inning. With runners on first and second, one out and the Nationals leading, 6-2, Cordero threw a 3-2 pitch to Kelly Johnson, who fouled it off. That's when Cordero felt the pain in the back of his shoulder. Cordero immediately called for head athletic trainer Lee Kuntz, and manager Manny Acta then called reliever Jon Rauch into the game.
Also, while Lo Duca will be the No. 1 catcher, Wil Nieves and Johnny Estrada will split the backup duties. Nieves most likely will see more time behind the plate and Estrada will see time as a pinch-hitter. Nieves has done an excellent job both behind the plate and with the bat and has an excellent rapport with left-hander John Lannan.
"Wil Nieves has done a phenomenal job catching," Bowden said. "He's done a phenomenal job with the bat. So yeah, I think we have three quality catchers and certainly we have guys that can hit, and guys that can catch and throw, and it's a good combination.
"As long as we can carry it, I think it's a good thing to have. It allows Manny to pinch-hit for the catcher. It allows him to double-switch, put a defensive catcher in if he decides. ... Normally I'm not a three-catcher GM, but the way we're structured, I think it will work out well."
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.