Rajon Rondo’s season-ending knee injury may doom the Boston Celtics this year and beyond, but Kevin Garnett doesn’t want his valuable teammate to rush his return to the court. KG told Rondo that he should think of his future first. Per the Boston Herald: “The first thing I told him was, do not play Superman,’ Garnett said. ‘Take care of yourself. I know you think you’re young, but you’re not that young. He’s old in a young body, if you will. But take it seriously. Go get second opinions. Live right … ‘He’s played through a lot of things you guys have no idea about, nor will I share now,’ Garnett said. ‘The game in Sacramento, he shouldn’t have even played that game. I’ve seen Paul (Pierce) play through some stuff, I saw Ray (Allen) when he was here muscle through some stuff. He’s a tough kid and I learned that the first day I got here. It’s no surprise. That’s why I said what I said to him: Hey, you’re a human being, take care of yourself.’ Coach Doc Rivers, whose tenure as player with the Knicks was marred by a torn ACL in 1993, isn’t surprised by the theory that Rondo kept playing after suffering the injury late in Friday’s loss in Atlanta. ‘It means he’s pretty tough,’ Rivers said. ‘I know when I tore mine, I was crying on the floor like a little baby. So, he actually thought it was his hamstring. He was telling me he thought he pulled his hamstring. And Dr. (Brian) McKeon, fortunately right before the game (yesterday), he got here and Rondo was telling him his hamstring was bothering him and he said, ‘Let me check it’ with his hands and I guess … I don’t know.’ Ironically, Rivers answered a question about his old ACL injury before Thursday’s loss to the Knicks. ‘Yeah, I shouldn’t have talked about it,’ he said. ‘Rondo will be fine. He just will not be fine this year. But he’ll be fine. We’ve got a guy in the NFL that we can look at, in Adrian Peterson, and whatever he did, that’s what we want to do. Because that was amazing. And that’s what Rondo will do.’”