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Denver, CO (SportsNetwork.com) - The Washington Nationals placed third baseman Ryan Zimmerman on the 15-day disabled list on Wednesday and recalled infielder Zach Walters from Triple-A Syracuse.

Zimmerman, 29, heads to the DL for the second time this season, this time with a right hamstring strain. He was hitting .362 with a .418 on-base percentage in the month of July.

Walters hit just .182 with three of his six hits being home runs during a 27- game major-league stint from April 13-May 27. He has collected 15 homers and 48 RBI with a .300 average in 60 games for Syracuse.