Nationals third baseman/left fielder Ryan Zimmerman has been diagnosed with a Grade 3 hamstring strain, reports MLB.com’s Bill Ladson (via Twitter). That is the most severe form of hamstring strain, involving a tear of half or more of the muscle, and could shelve Zimmerman for a significant stretch. The injury took place on July 22.

The Nationals have already been said to be probing the market for a possible third or second baseman, with the presumed intention of utilizing Anthony Rendon at whichever spot is not filled via trade. The seriousness of Zimmerman’s injury could increase the likelihood of an addition. Of course, the team could stick with its current alignment, with Danny Espinosa and Zach Walters sharing time at the keystone and Rendon playing his natural hot corner.

If Washington looks to make an addition, it would look to a market with relatively few everyday regulars seemingly available. Among potentially available third basemen, Adrian Beltre of the Rangers is the clear prize — if he’s put up for sale. The Nats were reportedly “rebuffed” in an earlier inquiry, but Texas is said to have had eyes on Triple-A Syracuse last weekend. The second base market does not contain many names that appear to be likely fits, though Aaron Hill of the Diamondbacks could be a possibility. His Arizona teammate, Martin Prado, has spent time at both positions and has been mentioned as a possible fit.