With the score tied at 4 and the Nationals batting in the eighth inning, Papelbon and Harper got into an argument in the dugout before engaging in a physical altercation, during which Papelbon grabbed Harper's neck. Coaches and teammates had to break up the altercation.
Papelbon said Saturday he and Harper had settled their differences. Harper accepted Papelbon's apology.
"My mistake was doing that in the dugout in front of a camera," Papelbon said. "I've got two young kids. They know that's not right, but it happens. I fully apologize for doing that but most of it's handled in the tunnel. [Harper is] a competitor, too."
Another baseball source said the Nationals are trying to trade Papelbon. They are trying to acquire Reds closer Aroldis Chapman, but the price might be prohibitive.
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the Time. He also can be found on Twitter @WashinNats. Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.