Doc Rivers asking his team to take another Game 7 approach Wednesday. (AP)

WALTHAM — It’s a theme that began last weekend after the Game 3 loss to the Knicks. Every game the rest of the series is like Game 7. It worked in Game 4 as the Celtics won, 97-90, in overtime but the Knicks still lead the series, 3-1.

“Like I told them, what’s the difference between being down 0-3 and being in a Game 7?” Doc Rivers asked rhetorically. “It’s no different. It’s an elimination game. The difference is your mindset. In a Game 7 you’re thinking, ‘Let’s win it to win it.’ When you’re down 0-3, you never know. You may have a couple guys making vacation plans, thinking you can’t do it. It’s all about the mindset. And that’s what I told our guys before the game the other night and that will be the message still. Each game you win, it is a Game 7. If you advance, you just advance to another game instead of to the next round. That’s got to be our mindset.”

Rivers knows veterans like Kevin Garnett, Paul Pierce and Jason Terry fully understand that message. The hope is that it’s filters to players like Avery Bradley and Jeff Green Wednesday night in New York.

“You know, Game 7s are all out,” Garnett said before Tuesday’s practice. “It’s just what they are. They’re your last opportunity to survive and your mentality can’t be anything different. We have no pressure at this point. It should be an all-out mentality and you should play with a free mind and an aggressive mind and take this thing one game at a time and see what happens. Other than that, we put [ourselves] in this position, and we can’t [complain] about too much.”

Did Sunday’s Game 4 OT win instill more confidence in the group as they hit the road?

“Don’t know,” Rivers answered. “I’m hoping that we had confidence to begin with, but I honestly don’t know. I think we are really looking forward to the next game.”

What was clear to Rivers and his coaching staff from watching film is that another 18 turnovers Wednesday in New York like they had on Sunday will end the season. Aside from turning the ball over, the Celtics need to repeat their offensive flow of the first half, when they shot 50 percent and built a 19-point halftime lead.

“Well, we have to repeat it,” Rivers said. “It’s clear when we play a certain way, and that’s in an attack mode, not settling offensively, moving the ball, getting in transition, we’re hard to stop. It’s also clear when we get into the half-court and slow the ball down we’re not that hard to stop and that’s obvious.”

Other nuggets from Tuesday practice from Doc Rivers:

Second chance points. Frustrating for KG? “That’s frustrating for him. And some of them were switches where we switch and Chandler is underneath with a guard. We got called for two face guard block outs, which is legal. And I think we have to explain that honestly to our official, because it doesn’t look legal and I agree with them in that, but it actually is a legal position. We’re telling our guards instead of backing up, turn around and face guard them and block them out that way. Your’e not going to get the ball, but they’re not going to either. So that’s something we’re trying to do. but their guards got a lot of rebounds too. Shumpert hurt us on the glass. Jason Kidd hurt us on the glass too. So we can’t give up the extra shots with the turnovers and the offensive rebounds and expect to win tomorrow on the road. We just can’t do that. So we have to definitely fix the turnovers first and then the rebounds second.

On admiring KG for hard work it takes to get ready? “No, people have no idea what he goes through, and you can’t unfortunately. But it really is watching him just in there now doing all the stuff that they’re doing, the stretching. He just plays because he loves it, and it’s will. A lot of guys would just not play anymore. The fact that he does and to the level that he does it, I mean he’s a rebounding machine for us right now, and we need it.”

What to expect from Melo with return of J.R. Smith from one-game suspension? “Well, listen, Felton took up all the slack for J.R. so that dynamic is that dynamic. Felton is going to come back, he’s going to be very aggressive. He’s going to want to wash away the demons that he created, and that’s fine by us. Melo is a problem every night against every team. And I don’t know if you hold him to 10-for-35 or if he goes 10-for-35. Him, LeBron and Durant, I’ve already said that about all three. You’re not sure if you’re holding them to 10-for-35 or he just goes 10-for-35, so we’re hoping that he goes or he hold him. Whichever way you want to have it. We hope it happens again.”

On KG getting 10 shots a game. Want to get him more? “Well, I don’t mind. They’re trapping, so it’s hard. Again, don’t get fooled by stats. If you threw it to him 40 times and they trapped every time, he’s still only going to get 10 shots. He’s getting the ball a lot, but they’re trying to take it from him a lot as well. I just wish we did a better job of taking advantage of it when they do trap him. That’s where I would say I’m the most disappointed with us offensively, because we work on it every day, and we really haven’t taken advantage of their traps and we have to do a better job there.”

Same with Pierce? “Yeah, exactly. It’s both. We know it’s no secret. They’re going to trap Paul, they’re going to trap Kevin and all year we’ve done a great job of really attacking traps, to the point where teams stopped trapping us. And for whatever reason, we just have not made the open shots. But honestly, I don’t think we made the right decisions. I thought we settled in the second half on the traps. We settled for long shots, quick shots, instead of attacking it back off the dribble, and we have to do that.”

On Jason Collins news: “Well, we had talked, so I wasn’t surprised by the article or the statement because we had talked about it recently though. So, other than that. no.”

Was it was talked about and was Rivers surprised? “I don’t know. I don’t know if I was surprised, or really didn’t care one way or the other. When he called me to tell me, and you could tell he wanted to tell me, I told him before he said it, ‘Jason, I could care less about what you’re about to tell me.’ And that’s how I feel, I honestly feel that way. I could care less what any of you guys do. It’s a nonfactor to me, and I know it’s a factor to a lot of people, I just have never understood why anyone cares about what someone else does. You know what I mean by that? And I told Jason that. I said it will be a nonissue eventually, but it will not be right now. And it will be news, and maybe it should be or shouldn’t be, I don’t even know the answer to that.

“No, he told me he was coming out. And I told him great, good. Let’s move forward. And I jokingly said, I wish you could have gotten me more rebounds, because that’s all I care about really at the end of the day.”

Paul Pierce on the key to the offense:
“I think we can’t allow their ball pressure to get to us,” Paul Pierce said. “I think sometimes we’re rushing. They’re going to get up into the ball, they’re going to pick up full-court. So, we’ve just got to be patient. We can’t have any unforced turnovers. A lot of times we have some of those. And when we drive to the basket, when we get into the paint, we have to be cautious of their slap downs. They’re not a big shot blocking team so they like to strip when you get in the lane, so we have to be very cautious of that.

“It’s got to be a collective effort. It has to come from all five guys. Even the point guards, the two guards, myself. We have to gang rebound. Kevin’s in there working, doing his job, and we can’t depend on that. There’s going to be nights when he’s not going to be able to get 17 rebounds, so we have to be able to collectively help him out on the glass and we have to do a better job of boxing out our man.”