The conclusion was that the 24-year-old Kershaw would not do further damage to the hip, which speculation indicates will need offseason surgery regardless, although nobody has confirmed that.
Mattingly said general manager Ned Colletti spoke with Kershaw to be assured the pitcher was "being 100 percent honest with us."
"He promised if he feels anything, he'll stop and not throw another pitch," said Mattingly.
"The last thing I want to be involved with is pitching Clayton Kershaw hurt. If I knew something that he shouldn't pitch, I couldn't sit here for that."
Mattingly said Aaron Harang would be on alert to take over, beginning with pregame warmups. Also, Mattingly said he would start A.J. Ellis behind the plate, because with his familiarity, he could spot a change in Kershaw's mechanics. Mattingly had wanted to rest Ellis, who is in an 0-for-28 slump.
"From there," said Mattingly, "we look at it like it's a huge game and he's ready to pitch. I'm not willing to give up. I've seen crazy things happen. Kersh is not giving up and the organization is not giving up. He's not in any more danger pitching than any other start."
Kershaw made it clear he badly wanted to pitch in the game, with the Dodgers 3 1/2 games out of the last Wild Card spot and 10 games remaining. Because he took 10 days to recover from his last start, Mattingly speculated that Kershaw might have one more start before the regular season ends.
"I don't know if I've seen anybody like him," Mattingly said. "What I love about Clayton, he not only has that talent but there's not any acceptance of anything he's done is good enough. I have to get better. That pursuit of excellence is not matched. I've watched [Derek] Jeter and he's pretty much the same guy, always moving forward. What's done in the past is over."
But Mattingly said Kershaw's "determination and work" to get healthy was more of a factor in the decision than Kershaw's desire to pitch.
"He wasn't ready to give up on the season," Mattingly said. "Ned talked to [president] Stan [Kasten] and ownership. I don't think anybody is not in the loop on where this is."
Mattingly previously named Harang to start on short rest in place of Kershaw, but Kershaw re-emerged after an impressive 20-pitch bullpen session on Friday. He went through his normal routine on Saturday as if he was planning to pitch.
Mattingly said he would be nervous about sending Kershaw to the mound if it had been his decision alone.