With Soriano having pitched four of the past five days during a six-game winning streak, Williams did leave the door open for giving him some rest should another save opportunity arise in Monday night's series opener against the D-backs.
The Nats have plenty of other experienced options, with right-handers Tyler Clippard and Drew Storen both having closed in recent years. Williams also named lefty Matt Thornton as a possibility.
"We want to give him the ball in the ninth inning," Williams said of Soriano. "He's been really good for us all year long, so we'll see how his health is, how his arm feels [Monday]."
Soriano began the season as the Nats' closer with 13 straight scoreless innings and seven straight save conversions. Through the first half, he had completed 22 of 24 chances while posting a 0.97 ERA and holding hitters to a .153 average.
But since the All-Star break, the 34-year-old has allowed 23 baserunners and 10 earned runs over 11 2/3 innings. Williams believes Soriano has been missing up in the strike zone, and Soriano agreed that his location hasn't been good.
That led to a third blown save in 10 tries on Sunday, when four of the five batters he faced reached safely, turning a two-run lead into a one-run deficit. Soriano walked off the field to a cascade of boos but didn't take it too hard. He heard louder while playing in New York for the Yankees, he said, and he knows that this time, he didn't do his job.
"Come back tomorrow and forget everything that happened today," Soriano said. "I want to do my job and come back tomorrow and see what happens."
Andrew Simon is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.