Jacob deGrom will start Sunday, Terry Collins announced before Friday night’s game against the Twins, answering a lingering question and possibly adding an extra layer of hope for the Mets in their drive for the postseason.

“We think he’s ready,” the manager said after watching deGrom throw in the bullpen. “He looked great, but we know how good he can be in the daytime.”

DeGrom was bothered by forearm tightness in his most recent games, but he has progressed enough to convince the Mets to give Noah Syndergaard an extra day of rest.

“Our expectations right now are to build him back up a little bit. He’s going to get three starts,” Collins said of deGrom’s likely schedule for the rest of the regular season. “We’re hoping we can get him back up to where, if we get in the postseason, he’s a viable option for us. We think he’s going to be fine, but we don’t have a crystal ball to know what’s going to happen here after he throws Sunday. The effort level is going to be pretty intense with him and we’ll just see how he bounces back from that. We’re just glad to have him back.”

That development contributed to a spate of promising health news for a team that has been reeling from injuries all season. Juan Lagares, recovered from left thumb surgery, was activated from the disabled list, where he had been since July 29. Lagares said he feels good enough to play defense and pinch run for now and expects to begin batting practice next week. Having a Gold Glove outfielder available late in games is enough for Collins, who said having Lagares available to bat “is a long shot.”

Lucas Duda (lower back stress fracture) also will be back Saturday, Collins said, and despite not having faced live pitching in four months, he could help off the bench. And Steven Matz (shoulder impingement) will throw a full bullpen session Saturday.

The only cloudy medical report came from Wilmer Flores, who took a cortisone shot in his wrist Thursday. “It doesn’t feel very good right now,’’ he said, “but hopefully in the next couple days it will feel better.”

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DeGrom shagged flies Friday but did not speak with reporters before the game. In Atlanta last weekend, though, he did promise not to get back on the mound too quickly. “I want to be out there, definitely,” he said then. “But at the same time I’ve got to be smart about it, make sure I am fully healthy before I go back out there.”