It went from bad to worse for Jayson Tatum and the Celtics.

First, Boston’s young star was ineffective. Then he suffered an injury. Tatum couldn’t get anything going, and then sat the final 20:48 of the Nets’ Game 2 blowout of the Celtics at Barclays Center with a scratched right eye.

“He tried to adjust to the light out there and he was really struggling. He got scratched pretty good,” Celtics coach Brad Stevens said after the 130-108 rout gave the Nets a 2-0 series lead. “It looks pretty red, it looks pretty swollen to me. I don’t know what the exact diagnosis is, but obviously he’s uncomfortable right now.”

For the Celtics to have any shot in this series, they needed Tatum to follow up his monster regular season with an even better performance. So far, the two-time All-Star yet to come close.

He didn’t shoot well in the opener, making just 6 of 20 shots, but at least he scored 22 points. He was worse Tuesday night, limited to nine points on 3 of 12 shooting as the Nets raced out to an early lead and cruised from there. Hounded by Nets star Kevin Durant, Tatum had as many turnovers (three) as made field goals, and only notched two assists.

“We need to get open for him,” said Marcus Smart, who scored a team-high 19 points. “We’re running plays for him, we’re doing everything that we can to help him. But at the same time, Jayson has to continue to be able to adjust to the defense that he’s seeing out there. Like I said, we just gotta continue to get open for him. We gotta continue to get in his eyesight and JT [has] to continue to make the pass to us, even if we’re making or missing them. Eventually, shots will fall and it’ll open up a lot for him.”

Said Durant: “We know he can get it going at any point, but I’m glad we were able to get a contest on most of his shots.”

Early in the third quarter, Tatum got inadvertently poked in the right eye by Durant and went down in a heap after gathering the ball. He tried to come back, but the eye didn’t feel right.

“It’s unfortunate,” Smart said. “When we’re struggling and our best player goes out with an injury, it’s tough. But he’s in good spirits, we’re in good spirits. He’s going to be OK. I don’t think it’s as serious as most people probably thought, which is good for us, good for him. And, like I said, he’s in good spirits. I’m sure he’ll be playing in Game 3 and we’ll get right back to it.”

His health is now a major question as the series shifts to Boston. The Celtics are hopeful the home crowd will help them, pointing to how well the Nets played in front of their fans after playing in front of near-empty arenas during the regular season.

But if Tatum isn’t right — or he can’t perform better than he has so far in the series — it may not matter.