Washington, which leads the National League East by 3 1/2 games, had previously set a 160-inning limit for Strasburg, who turns 24 on Friday. That number may no longer apply, but Rizzo told ESPN on Wednesday that he alone will make the call.
"There is no magic number," Rizzo said. "It will be the eye test. [Manager] Davey [Johnson] won't decide, and ownership won't decide. It will be the general manager, and that's me."
Strasburg is 10-4 with a 2.66 ERA and leads the NL in strikeouts, with 135 in 105 innings. The No. 1 overall pick in the 2009 First-Year Player Draft underwent Tommy John surgery as a rookie in 2010 and pitched in only five games after returning late last season.
With the Nationals on track for their first playoff appearance since moving to Washington in 2005, debate already is raging about how the club should handle Strasburg. Rizzo now has put all of that pressure on his own shoulders.
"We'll do it my way," he told ESPN. "I have the full support of ownership on this issue. It's my decision, and I've made it. There will be no going back on the decision."
Although a Strasburg-led rotation surely would serve as a significant asset in September and October, Rizzo also has the franchise's long-term future in mind. He was adamant that once the Nationals shut down Strasburg, he will not return until Spring Training.
"When we signed Stephen, I made a promise to him and to his parents that I would take care of him, and that's what we are going to do," Rizzo said. "I told them we would always do what's best for him. This is a kid who has never pitched more than 123 innings in a year.
"We are looking at not only competing for the playoffs this season but also in '13, '14, '15 and beyond. Stephen is a big part of those plans, and I will not do anything that could potentially harm him down the road."
But no matter who is making the decision or how well intentioned it is, Strasburg plans to fight it.
"I said it recently, they'll have to rip the ball out of my hand," Strasburg told ESPN on Wednesday night, "and I mean it."
Andrew Simon is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.