Williams challenged the call, and after review it was overturned. LaRoche had tagged Sweeney before he reached the base.
Cubs manager Rick Renteria challenged a play in the bottom of the eighth inning, but this time, the call would stand after review.
Nationals center fielder Denard Span connected on a line drive to right field and rounded first base to try and stretch the hit into a double. Right fielder Nate Schierholtz fielded and threw to shortstop Starlin Castro, who was covering second, but Span appeared to avoid the tag and slid safely into the base.
Renteria challenged the ruling on the field, and after review, Span remained on second. He later scored the go-ahead run on Ryan Zimmerman's single.
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. He also could be found on Twitter @WashingNats. Daniel Popper is an associate reporter for MLB.com. He also can be found on Twitter @danielrpopper. This story was not subject to the approval of Major League Baseball or its clubs.