Expect chaos, but here’s what we’re watching for in Celtics-76ers Game 7

BOSTON — This Celtics-76ers series has brought out a whole range of emotions. Anger. Joy. More anger. Relief.

You name it, and Celtics fans have felt it as the Celtics have had to fight to get to a Game 7 against one of the franchise’s biggest rivals. And now we get what will likely be another anxiety-filled affair to share with everyone’s Mother’s Day plans.

We were all hoping that the Celtics would at least get one somewhat easy round this postseason, but we should know better by now. If there is a path that makes life more difficult, that is the route these Celtics are going to take.

So here we are with a winner-takes-all, anything-can-happen, hold-on-to-your-butts Game 7 on Sunday. What’s going to happen? Who the heck knows. It’s not worth trying to predict which Celtics team — or 76ers team, for that matter — is going to show up.

There is one thing we can tell you: One team is going to win and advance to the Eastern Conference Finals. The other is going home for the summer.

At least with all of these Game 7s over the years, this Celtics core has experience. And the Tatum-Brown-Smart triumvirate is 4-1 in this situation.

Here’s what we’ll be watching for when this Game 7 tips off Sunday at TD Garden.

Tatum’s start

OK Jayson, enough messing around. He’s attempted five shots in each of the last three first quarters, and he’s missed all 15 of them. For the series, he’s just 8-for-30 in the opening frame, which includes a ghastly 2-for-13 from deep. Enough is enough.

One thing Tatum doesn’t lack is confidence, which he made clear after catching fire late in Game 6 and nailing four 3-pointers to help the Celtics keep their season alive. But if he wants everyone else to think he’s one of the best basketball players on the planet, he needs to be a lot more consistent.

Tatum’s slow starts came back to bite them in Games 4 and 5. They survived it in Game 6 thanks to his late flurry from deep. And overall, he’s still been pretty good this series, somehow averaging 25.3 points on 41.7/31.9 shooting splits. You’d think his shooting numbers would be in the sewer because of his struggles over the last three games, but they’re not bad.

And at least Tatum is making an impact everywhere else, snagging rebounds, making great passes, and really mucking things up on defense. At least he’s not letting his woeful starts affect his play elsewhere.

But he really, really needs to get going early on Sunday. Otherwise he may not get another chance to shake these early-game issues.

Which Harden shows up?

This is the real X-factor for the 76ers. Will it be the Harden that drops 45 points, or the one that struggles to score 15?

While the Celtics’ defense has struggled with the Harden-Embiid pick-and-roll sets, it has done a solid job limiting Harden’s clean looks for most of the series. When Jaylen Brown is glued to Harden, it keeps him from being the true James Harden.

But if he’s allowed to be the Houston-era James Harden, it creates issues all over the floor for the Boston D. Keep Harden flustered, and everything falls on the shoulders and achy knees of Joel Embiid.

Al’s “elite” shooting  

Al Horford was laughed at last week when he mentioned his “elite” shooting. How could anyone laugh at Al, especially with those eyes?

He used that laughter as inspiration, and bounced back from a 2-for-14 start from 3-point range in the first two games to hit five of his seven threes in Game 3. The Celtics won that game easily.

Well, maybe someone else should laugh at Al. Because he’s been worse than first-quarter Tatum since lighting it up last Friday, hitting just two of his 16 3-point attempts in Games 4-6. He’s 0-for-9 from downtown the last two games, and has hit just one of his 13 shots from the floor for a grand total of two points.

It hasn’t hurt the team too much thanks to guys like Jaylen Brown, Marcus Smart, and Malcolm Brogdon picking up the scoring slack. But if Al is going to launch that many shots, he needs to hit a handful of them.

With an extra day of rest between Games 6 and 7, maybe we’ll get a vintage Horford performance and he’ll be the Game 7 out-of-nowhere difference maker that Grant Williams was last year at this time. At this point, just a few makes — from anywhere — could make a difference.

Heart and hustle

Jaylen Brown called out Celtics fans Thursday night, mostly in a way to make sure the Garden crowd is really raucous and wild come Sunday. And he’s right, that place better be an absolute madhouse.

But on the other end, the Celtics haven’t given fans much to cheer about at home this postseason. The Celtics are 3-3 on their home floor during the postseason, and just 9-9 dating back to last year’s run to the Finals. There have been some really good wins in that mix, but just as many frustrating and inexcusable loses.

So if the Celtics really want to get fans on their feet — and keep them there —  they need to come out with the same level of intensity. They were completely flat in Game 5, and showed more heart and grit in the opening minutes of Thursday night’s win than they did all of Tuesday night.

It won’t take much. Hit the deck for a loose ball. Take a charge. Toss up a few lobs to Rob Williams. And blocks by the big fella always fire up the crowd.

But if the Celtics want the fans to go wild, they need to give them a reason to go wild. Brown has done plenty of that as the team’s best player this series. Maybe his comments Thursday were not just for the fans, but for the rest of his team as well.