LOS ANGELES — After Clayton Kershaw had a follow-up examination on his sore back, the Los Angeles Dodgers said they remain unsure when the three-time NL Cy Young Award winner will return.

Kershaw said after last Sunday’s loss at Pittsburgh that he felt back stiffness. He received an epidural injection and was placed on the 15-day disabled list after an examination by Dr. Robert Watkins revealed a mild disk herniation.

“We don’t know much more than we did a few days ago,” Dodgers President of Baseball Operations Andrew Friedman said Sunday. “Everything that’s happened in the three or four days since the epidural has been extremely positive. That being said, I think we’ll know more in the next week. We just need to give it time past the epidural to get a sense of improvement, and then we’ll go from there.”

Friedman is confident Kershaw will avoid surgery.

The 28-year-old left-hander will undertake a five-step program and start throwing at some point.

“Obviously that will be a big first step,” Friedman said.

The program centers around strengthening Kershaw’s core muscle group.

“Whenever somebody has anything in the back, the core strengthening helps with the back in that process of when you start throwing, which obviously is what everybody cares about,” Friedman said.

Kershaw said Saturday that his back had not hurt when he pitched, but had been bothering him for an extended time. He said that it had been taking him longer and longer to get loose, and that until Monday he chalked it up to routine wear and tear.

Unbeaten in his 10 previous starts, Kershaw (11-2, 1.79) had his second-worst outing of the year against the Pirates, giving up four runs and nine hits in six innings.

ROCKIES: Tyler Chatwood is scheduled to be the starting pitcher for Colorado on Tuesday against the San Francisco Giants, Rockies Manager Walt Weiss said.

Chatwood, out since June 18 with a back strain, threw five shutout innings in a rehab start for the Class A-Modesto Nuts on Thursday night, throwing 66 pitches.

CUBS: Outfielder Chris Coghlan was placed on the 15-day disabled list with a right ribcage strain.

Nationals: Right-handed pitcher Joe Ross (right shoulder inflammation) was placed on the 15-day disabled list. He labored through 51/3 innings against the Reds on Saturday allowing a season-high 10 hits and four earned runs with a noticeable drop in velocity.