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9/3/2013 7:27 P.M. ET

Harper will rest hip in Philly series finale

PHILADELPHIA -- Nationals outfielder Bryce Harper was hitting third and playing left field on Tuesday despite dealing with a left hip injury which manager Davey Johnson didn't know about until right before Monday's game.

Johnson noticed that training assistant John Hsu was working on Harper's hip. Had Johnson known about Harper's injury, Johnson would have given Harper the day off and played Denard Span instead.

"I think players sometimes don't want the manager to know they are getting treatment," Johnson said. "But I need that. It's part of the information I could use to ensure that they can get through the year injury free. They might be able to play with that injury, but it might be better to take a day off and let somebody else [play]."

Johnson plans to give Harper the day off Wednesday, and the team has a day off Thursday.

Harper didn't have any issues with the hip on Tuesday, going 0-for-5 and scoring two runs.

Walters earns September callup with strong year

PHILADELPHIA -- The Nationals added a few players to their active roster Tuesday. They selected the contract of shortstop Zach Walters and recalled left-hander Xavier Cedeno and outfielders Corey Brown, Jeff Kobernus and Eury Perez from Triple-A Syracuse. Before Tuesday's callup, only Walters, 23, didn't have Major League experience with the club this year.

Walters, 23, joins the Nationals after hitting .253 with a career-high 29 home runs and 77 RBIs in 134 games for the Chiefs. Walters paced Triple-A with 66 extra-base hits, while his 29 homers tied for the Triple-A lead with Buffalo's Mauro Gomez.

Walters will not see much playing time this month, because manager Davey Johnson plans to play his regulars during the Wild Card race. But that does not take away from the fact that Walters made significant improvements with the bat this season.

When he arrived in Spring Training, Johnson wanted Walters to change his stance, be more upright in the batter's box and become a power hitter. Walters was so impressed by Johnson and his tutoring that one person familiar with Walters said he idolizes the skipper.

Walters said he wanted to improve because of Johnson's stature in the game of baseball.

"He came up, talked to me and made me feel that I was part of the team," Walters said. "For him to show that kind of time and put that effort in me. ... So when he said something, I took it to heart."

After getting off to a slow start, Walters credited Syracuse hitting coach Troy Gingrich for getting him straightend out at the plate. Walters improved his mental approach and made some physical adjustments.

"It made me more consistent, as I would say," Walters said.

Walters said he needs to improve his defense. An injury to his left eye played a role in him making 29 errors. Most of them came while playing shortstop.

"[During batting practice], I took a ground ball in the eye in Syracuse," Walters said. "I started the season off good. From that point on, [the eye] acted up. It felt almost like a headache. I felt good with my hands while working with [manager Tony Beasley]. When everything is good, it's going good. Once my left eye starts acting up, it's little hard out there."

With Walters in the big leagues, it means that Danny Espinosa didn't get the call back to the Nats and was sent home to California. Johnson reiterated on Tuesday that he considers Espinosa an everyday player, but with the roster set up the way it currently is, Espinosa would hardly see any playing time. He would be no more than a pinch-runner, pinch-hitter or defensive replacement.

"I don't think he would be happy with it. He has a lot of talent, "Johnson said. "He can be more mad at me. I did not want him here and not have him in the lineup."

Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. He also could be found on Twitter @WashinNats. This story was not subject to the approval of Major League Baseball or its clubs.