The Kristaps Porzingis blockbuster wasn’t cheered by all, especially not by rookie Kevin Knox.

It was a double whammy for Knox. The Knicks lottery pick saw a bright future with Porzingis as a forward tandem. And in the short term, Knox lost his top mentor, veteran Courtney Lee, who had taken the 19-year-old under his wing.

“He was the guy I talked to all the time for advice,’’ Knox told The Post. “He was the person I talked to if I needed help with anything on the court or off the court. It’s hard to see him go. We talked a lot. He gave me a lot of information.”

It’s been a roller-coaster rookie year for Knox, who is averaging 12.6 points per game but appears to be hitting the rookie wall, although Knox responded with one of his strongest outings of the last two weeks against Toronto on Saturday with 20 points, making 4-of-9 3-pointers.

“[Lee] said to stay in touch, that we’ll work out over the summer, keep working hard and the sky is the limit for what I can do,” Knox said.

Even if Porzingis didn’t travel to road games and never was cleared for practice, Knox said the 7-foot-3 Latvian made an impact on him.

After Knox was taken ninth in last June’s draft, Porzingis Facetimed him that night from Spain — a development president Steve Mills found encouraging. It was fleeting, however.

“I definitely wanted to play with him and I wasn’t able to,’’ Knox told The Post. “He’s an All-Star. I wish him the best of luck. He helped me on the court and off the court. I still got to talk to him a lot. Just to learn from an All-Star is cool, but it would’ve been cooler to play with him on the court.”

On the bench during games, Porzingis talked to Knox when he saw little things he could do better. But they never had the opportunity for anything to happen between them on the court.

“He was definitely teaching us,’’ Knox said. “Unfortunately, he didn’t want to be here long term.’’

Knox’s offensive efficiency and defense have been at issue. Even against the Raptors, Knox shot just 7-of-21 overall, leaving his shooting percentage for the season at 36.7 percent.

However, Lee couldn’t say enough about Knox’s potential. Knox was named last week to the All-Star Game’s Rising Stars Challenge as an injury replacement.

“He’s definitely going to be a stud man,’’ Lee told The Post in Dallas last week. “He’s still a child. He has those moments when he goes out for 30 points and the next game it’s five. It’s him understanding the NBA and you got to be consistent.

“He’s going to hit a lot of bumps before he figures it out but he’s on the right path. He’s a kid who’s willing to work and learn. I showed him an after-practice shooting routine and he’s doing it on his own the next day. Kevin is a guy after every practice is working on his jumpers, ball-handling and his floaters. He’s making those shots in a game now.”