The Heat will need their 2 stars to be on point in Game 6 after struggling in a Game 5 loss in Boston.

MIAMI – The locker-room wisdom that got the Boston Celtics’ minds right for Games 4 and 5 of their Eastern Conference Finals series against Miami came from an unassuming source. Matt Reynolds, a member of coach Joe Mazzulla’s staff, spoke up after Tuesday morning’s film session.

“Don’t ruin the season off a bad week,” one of the players said, recalling Reynolds’ message.

Simple yet profound, that remark suitable for a fortune cookie got the Celtics’ minds off their miserable 0-3 start to the series and onto the team they had been, and how they’d played, for most of this 2022-23 season. They got much more aggressive defensively, packing the lane to pester the Heat inside. They stopped jacking up early shots, were careful with the ball and resumed trusting each other, all of which had them roaring back with consecutive victories, 116-99 on the Heat’s court Tuesday and 110-97 at TD Garden Thursday.

What Boston faces now, however, might require someone with more oratorical chops. No slight to Reynolds but this seems like a job more suited to a guy like Winston Churchill, the statesman who coached Britain through World War II relying on a good cigar and a BBC radio microphone.

Here’s one of Churchill’s quotes that seems most pertinent now: “When you’re going through hell, keep going.”

Having to go into Miami’s arena, still down 3-2 and confronted Saturday night (8:30 ET, TNT) by a fully engaged and agitated Heat team, surely is a version of basketball hell. Virtually no wiggle room, no margin for error, for 96 minutes already and, to be successful, another 96 to go.

Sure, the Celtics have the momentum in the series and appear to have rediscovered their best selves. They are, by consensus, the more talented team and lately have put those talents to great use.

But Boston’s face-saving revival over basically the past six quarters of 20 so far in this competition – they were down 56-50 at halftime of Game 4 – has led to some irrational exuberance. The chance that the Celtics might do something that no NBA team in 150 previous tries has managed – digging out of an 3-0 hole to win a playoff series in seven games – now gets talked of as if it’s a foregone conclusion. Such is the verisimilitude of playoff basketball – the hot hand and the latest narrative hold sway.

The reality, however, is Miami gets Game 6 at home, the first of two chances still to eliminate the Celtics and advance to the NBA Finals for the second time in four postseasons. Boston and its fans would swap positions in a heartbeat. Having spent most of the past two weeks as front runners in this thing, there’s a sense of urgency returning for the Heat, a condition to which they typically respond well.

Guard Gabe Vincent, who pushed Miami’s pace while averaging 17.5 points and hitting half his 22 3-pointers in the first four games, sat out Game 5 but his left ankle sprain is improving. Role players Caleb Martin and Max Strus could feel more comfortable at home again. And the Heat might have stumbled onto more help when forward Haywood Highsmith, after logging only token minutes prior to Thursday, shot up to 36 minutes good for 15 points.

Most of all, the Heat’s two leaders, Jimmy Butler and Bam Adebayo, face the biggest challenges. Neither played in the final quarter last game, their team’s fate sealed, their performances mediocre. Adebayo had 16 points and eight rebounds, but also six turnovers. Butler took only 10 shots, scored 14 points, was a team-worst minus-24. Playoff Jimmy? More like Play-In Jimmy.

None of the Heat sound as if they’re buying into the notion that this one, Game 6, already is their Game 7. That is, lose Saturday and defeat back in Boston on Monday is assured. Butler and Adebayo aren’t confusing Game 6 with anything else. They don’t anticipate needing a Game 7, a big difference from dreading one.

“We are always going to stay positive, knowing that we can and we will win this series,” Butler said. “We’ll just have to close it out at home.”

Said Adebayo: “Why would we lose confidence? When we started this journey, nobody believed in us. Everybody thought we were going to be out in the first round. Everybody thought we were going to be out in the second round. And now we are here one game away. For us, we’ve always had confidence and that’s not going to go away.”

One tactic Boston might want to try is to force Butler to guard and get a few whistles on him. So far, the Heat forward has shot 38 free throws while committing only seven fouls. He stays on the floor as long as Miami needs him to be.

The Celtics, meanwhile, have been riding a happy wave of 3-pointers. They made 34 to Miami’s 17 in Games 4 and 5, a 51-point advantage. In the first three games, the Heat had the edge at plus-39 points. Boston has yet to demonstrate it can win a close game or one in which its bombs aren’t landing. Will Jayson Tatum, Jaylen Brown, Marcus Smart and Derrick White have the same bounce, the same energy at the other end?

Those are the sort of things that will determine if this is the series finale or if the teams are playing again Monday with history on the line. Basketball factors and individual performances, not slumped shoulders or oddsmakers’ probabilities.

“Who cares about mood?” Heat coach Erik Spoelstra said late Thursday. “I think so much of that is overrated. It’s a competitive series. You always expect things to be challenging in the conference finals. One game doesn’t lead to the next game. Based on all the experience that we’ve had, it doesn’t matter in the playoffs. It doesn’t matter if you lose by whatever.”

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Steve Aschburner has written about the NBA since 1980. You can e-mail him here, find his archive here and follow him on Twitter.

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