Greinke has been dealing with elbow discomfort for the last month and an MRI two weeks ago revealed no structural damage. Greinke compared the discomfort to soreness behind the elbow that he felt in Spring Training of 2013.
But Greinke said he was confident he would be able to pitch Saturday and not go on the disabled list. He said he "can't guarantee I'll be good from here on out, but I don't plan on having an issue with it."
He previously said he's pitched through similar discomfort in other seasons. He said he couldn't quantify his level of concern, adding: "I expect to pitch at a 100 percent level, but I don't expect to feel 100 percent."
Mattingly said the club is confident the two extra days of rest will be sufficient.
"He's had some little elbow discomfort," Mattingly said. "I don't think it's anything. He's not that concerned. He kind of notices everything like all these guys do. I don't think he really wanted to miss a start, but we felt like we're better off getting him of couple extra days for the long term.
"You're concerned from the standpoint that he doesn't feel 100 percent. I think there would be a lot more concern if they'd seen damage or any changes in the MRI."
Greinke, who leads the club in innings pitched and threw an inning in the All Star Game instead of giving his arm a break, has lost four of his last five decisions.
"I haven't pitched great lately. I don't know if this had much to do with it," said Greinke, who has skipped his last three between-start bullpen sessions. He played catch Wednesday.
The Dodgers went through a stretch of 20 games on consecutive days that ended with a day off Monday. They had hoped to get the Thursday night start from Greinke, then give him needed rest because they have off days next Monday and Thursday.
Greinke's injury follows the placement of five pitchers on the disabled list this month, including starters Josh Beckett and Hyun-Jin Ryu and swingman Paul Maholm, leaving few options to replace Greinke in the rotation. Despite the acquisitions of starters Roberto Hernandez and Kevin Correia, organizational depth has been depleted by season-ending injuries to starters Stephen Fife and Ross Stripling.
Ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.