Clarke Schmidt had work to get in Sunday, but some brutal conditions at Yankee Stadium made that difficult.

After the Yankees’ regular-season finale was delayed 91 minutes by rain, it continued as Schmidt took the mound and mustered his way through four-plus innings in a 6-4 win over the Pirates.

“We were very surprised we were trying to grind that one out,” Schmidt said. “We have playoffs coming up, and it’s a high injury risk. Even guys running to first base were falling over. But happy to make it through healthy, and everyone else made it through healthy, and we came away with the win.”

Schmidt said Pirates starter Bailey Falter came up to him in the outfield as the two were starting to warm up in the rain and asked what they were doing.

Once the game started, the grounds crew had to reapply dry dirt to the mound, infield and home plate area in between almost every half-inning.

Vying with Luis Gil for a start in the ALDS, Schmidt said he held back from his highest gear Sunday to make sure he did not injure himself in the wet conditions.

“At times, you couldn’t really find the rubber from all the dirt that was covering the mound,” Schmidt said. “The cleats weren’t gripping. And it was hard to grip the ball because the rosin was so wet, so if you touched the rosin, it actually got worse.

“Obviously, brutal conditions, but I didn’t have great execution regardless, so I didn’t put myself in a good spot.”