WASHINGTON -- Carlos Maldonado's sore back rendered him unable to hit once again Wednesday night, and now it will send the catcher to the disabled list. As a result, first baseman Tyler Moore was recalled from Triple-A Syracuse in a move manager Davey Johnson announced following Wednesday night's 5-3 victory over the Mets.

"It's a little sore right now, and I'm just sad that it happens," Maldonado said, adding that he believes the injury happened sometime during the Nats' 7-2 win over the Braves in Atlanta on May 27. "I'm trying to get better as soon as possible."

Maldonado is the Nats' fourth catcher to suffer an injury and the third to go on the DL this year. Moore, meanwhile, will begin his second stint with the team. In 19 at-bats earlier this season, Moore batted .158 (3-for-19). His last game with the Nats came on May 26, when he was 0-for-2 with one strikeout against the Braves.

"It's exciting," Moore said. "I got the call probably yesterday about 6 or 7 [p.m.], just tried to get out here as fast as I could."

Jhonatan Solano will be the backup catcher in Maldonado's place and got the start in place of Jesus Flores on Thursday afternoon against the Mets. Solano was initially called up on May 28 and played in two games against the Marlins May 29-30, going 1-for-4 with a double. While at Triple-A Syracuse, Solano was a reliable defensive catcher who batted .250/.298/.288 in 13 games.

"I'm happy, but feeling sad for Maldonado," Solano said. "The opportunity is huge. When they tell me to play, I put 100 percent on the field."

Lidge activated, while Rodriguez lands on DL

WASHINGTON -- The Nationals activated right-hander Brad Lidge from the 15-day disabled list Thursday and placed right-hander Henry Rodriguez on the DL with a strained right index finger, retroactive to Wednesday.

After the Nats' 3-1 loss to the Mets on Thursday afternoon, manager Davey Johnson said Lidge will be available when the team travels to Boston for a three-game series with the Red Sox beginning Friday night.

"The trainer came to me today and said that Henry was getting treatment every day for that finger, the index finger on his right hand," Johnson said. "Immediately, even though I liked the way he threw with the bum finger on Tuesday, I just told Henry, 'We just have the luxury right now ... if this was in July or August, I wouldn't even be considering it.'"

Lidge underwent hernia surgery on May 1 after making seven appearances in April. In seven innings, Lidge posted a 5.14 ERA with seven strikeouts and seven walks. Lidge made two rehab appearances with Class A Potomac, the most recent coming Wednesday night against Frederick. Lidge struck out two while pitching a hitless eighth inning.

Rodriguez, meanwhile, has been mostly ineffective, posting a 5.14 ERA in 21 innings.

"In talking to [pitching coach Steve McCatty], any time you have a strained joint, it's going to nag you for a while," Johnson said. "The thought process was, well let's just nip it right in the bud and not have something lingering all year long with him. Certainly, he's too valuable an asset. We want to get rid of it right now. We have the luxury of having a lot of guys who are ready to pitch."

Harper says he's OK after tweaking back

WASHINGTON -- The Nationals received a scare Thursday afternoon when Bryce Harper appeared to aggravate his sore back late in a 3-1 loss to the Mets.

With one out in the top of the ninth inning, Mets third baseman David Wright blooped the ball to short right field. Harper, who had switched over from center field in the sixth, charged hard after the ball and dove for it, but was unsuccessful. After throwing the ball into the cutoff man, Harper went back down to the ground in apparent pain.

"When he dove for the ball, I thought he just knocked the wind out of himself," Washington manager Davey Johnson said. "That predominately was the case. He also has been nursing a kind of tender back. So we'll have to monitor him pretty close."

Johnson added that Harper had been receiving treatment, a previously unheard revelation. Harper, for his part, repeatedly insisted after the game that he was fine.

"[It was] kind of sore, I was just trying to take a minute," Harper said. "I'm good. I'm totally fine to play, and I won't be out of the lineup."

Later, Harper was asked when he initially hurt his back. He responded, "I didn't hurt it. I'm good. Don't worry about it, I feel great."

Harper finished the game 0-for-4 with two strikeouts, dropping his average to .276.

DeRosa cleared, will start rehab stint soon

WASHINGTON -- Though Mark DeRosa's left oblique injury will probably linger, Nationals manager Davey Johnson said doctors have cleared the veteran utility man to play. DeRosa will have a rehab assignment with Class A Potomac and could be activated in a few days.

"The doctor cleared him, but that's the thing, it's probably going to be lingering a little bit, but it's going to depend on can he play with it without it getting worse," Johnson said. "Mark feels he can, so I'm going to let him go out. For me, with as much as experience as he's got, if he can go through a couple of days without aggravating it any worse, I'll activate him."

DeRosa has also been spending time in New Jersey to be with his father, Jack, who is battling cancer.

Worth noting

• With Brad Lidge rejoining the Nationals' bullpen and right-hander Ryan Mattheus set to rejoin the team soon, Johnson said the Nats could be carrying as many as 15 pitchers. Mattheus has been dealing with an injured left foot, but Johnson said he did some pitching and fielding practice recently that he "passed with flying colors."