DENVER -- If expectations weren’t high enough for Los Angeles Dodgers southpaw Clayton Kershaw, his manager might have added a little bit to them.

Before Kershaw took the mound Friday at the hitter’s haven that is Coors Field -- with 28 consecutive scoreless innings on the line -- Don Mattingly threw more onto his 26-year-old pitcher’s plate when he said he thought the reigning National League Cy Young winner hasn’t yet hit his ceiling.

Asked if he thought the game’s best left-hander could get even better, Mattingly answered without hesitation.

“Oh, I think he will,” the Dodgers manager said in the visiting dugout.

It will be tough for Kershaw to improve -- at least numbers-wise -- on what he’s already done, though. He has a 2.04 ERA this season and an MLB-best 2.19 ERA since 2011. He’s struck out at least nine batters in eight of his 12 starts this year and has given up more than three earned runs only once.

Mattingly, however, still thinks there is more to his All-Star pitcher.

He has seen Kershaw improve from a great pitcher to a historically great pitcher in just a few years. He remembers when the Texas native came into the league, with only two pitches to his arsenal and consistently struggling to hold on runners.

But things progressed quickly, and Kershaw grew up and got better. Today, he has four pitches and proven control with all of them, having walked more than two batters only once this season.

Indeed, it might only get better, his manager said.

“He still doesn’t use his changeup probably as much as he could,” Mattingly said. “That pitch is still there and developing. I still think there are times when the more he gets the ball to the opposite side of the plate, it’s lights out. If he gets the ball to the outside of the plate as much as he is able to get the ball in on righties and away to lefties, it will [be good].”

Kershaw faced the Colorado Rockies on Friday after striking out 15 in a no-hitter against them a couple weeks ago at Dodgers Stadium.