LOS ANGELES -- The Los Angeles Dodgers altered their pitching rotation Wednesday to give Zack Greinke two extra days of rest as he tries to pitch through discomfort in his right elbow. Clayton Kershaw, who was originally scheduled to start Friday against the New York Mets, will instead go Thursday against the San Diego Padres on his normal four days of rest.

Greinke has been feeling something in his elbow for about three weeks, but has not missed a start. Dodgers manager Don Mattingly said Greinke underwent an MRI exam two weeks ago that showed no structural damage.

"You're concerned from the standpoint that he's not 100 percent, but if he keeps feeling like he is right now, I don't think he feels it's a [disabled list] injury and I don't think anybody feels like it's a DL type of thing," Mattingly said.

Greinke has not thrown a between-starts bullpen session for the past three weeks, instead throwing off flat ground.

Greinke said soreness in his elbow "comes and goes," in general during the season. He compared the injury to a runner having a sore foot and continuing to run with it.

"I guess I don't really have a percentage or level of concern that I can describe," Greinke said. "I don't expect to be pitching at 100 percent. I mean, it's possible, but I wouldn't guarantee it, that's for sure."

Kershaw, a front-runner for the NL Cy Young award, was told on Tuesday that he likely would make Thursday's start and he spent part of Wednesday afternoon breaking down Padres hitters with catcher A.J. Ellis. Kershaw will get an extra day of rest before his next start, Mattingly said.