SAN DIEGO — Travis d’Arnaud suffered a setback on Saturday when his first throwing session since landing on the disabled list was cut short because of discomfort in his injured right shoulder.

Manager Terry Collins said that d’Arnaud will likely refrain from throwing for a few more days before attempting another session.

“Pretty discouraging for him and us,” Collins said. “But once again, there’s a process involved and maybe we didn’t wait long enough.”

D’Arnaud landed on the DL on April 26 with a strained right rotator cuff. He will continue hitting and catching drills as he waits for his shoulder to get strong enough for throwing.

Before going on the disabled list, d’Arnaud was in the midst of a slow start, hitting just .196 in 46 at-bats in 13 games. But thus far, his replacement hasn’t faired much better.

Kevin Plawecki entered play on Saturday hitting just .200 since taking over starting catching duties.

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Harvey Day

Just how long will Matt Harvey continue to be ordinary? The Mets will find out more when their underperforming ace takes the mound in Sunday’s series finale.

“Matt’s feeling good,” Collins said. “There’s no arm issues, there’s not of that stuff. He’s just got to make better pitches and he knows that.”

Harvey (2-4, 4.76 ERA) has been pedestrian this season, a fact that hasn’t sat well with the former All-Star.

“You’re talking about one of the best pitchers in the game who’s not pitching like we know he can,” Collins said. “Sure he’s frustrated, that’s the easiest word to use, and I don’t blame him. We’re all in the same boat.”

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Extra time

Reliever Josh Edgin will remain with Triple-A Las Vegas when his rehab assignment ends on Sunday. Edgin, who is coming back from Tommy John surgery, is not yet cracking 90 mph with his fastball.