The Celtics can’t afford to have Jaylen Brown’s second-half slump in Game 6 carry over to Game 7

A second-half slump from Jaylen Brown played a big part in Miami's Game 6 win Friday. Can he rebound in Sunday's Game 7?Matthew J Lee/Globe staff

The Celtics are going to need Jaylen Brown to show up in a big way in Game 7 of this exhausting Eastern Conference finals series with the Heat.

He may well do it — even though they’re still waiting for him to show up for the second half of Game 6.

Brown scored 20 points in the Heat’s relentless 111-103 series-tying victory Friday night at the Garden, but just 2 came in the second half. He did not score a single bucket and attempted just two shots after the break.

His lone pair of second-half points came on free throws with just under eight minutes remaining to cut the Miami lead to 89-87.

It was either team’s game to win at that point. A few minutes later, the Heat seized control and the Celtics faded in part because of a pair of free throws Brown missed.

Jaylen Brown is fouled by Miami's Max Strus in the first quarter of Friday's Game 6.Matthew J Lee/Globe staff

With 2:06 remaining and the score tied at 99-99 thanks in large part to an extraordinary performance from Derrick White (22 points, 4 of 5 from 3-point territory), Brown went to the line with a chance to give the Celtics the lead.

Brown can be an inconsistent free-throw shooter, with his slow and methodical release, but he had made his first seven attempts to that point, and the Celtics as a team had missed just one. But both attempts ricocheted off the rim.

Jimmy Butler, who was in full beast mode (47 points) after looking hobbled in Game 5, followed the misses with a conventional 3-point play on the other end, and the Heat iced their win at the foul line. Brown’s charge on an attempted dunk with 1:21 left — initially called a block on Victor Oladipo before it was overturned — was the Celtics’ last wheeze.

If the Celtics win this series, the Game 6 loss will be remembered as a blip on the road to the Finals. Should they lose Sunday night in Miami, it goes down as an all-time regrettable playoff defeat.

Brown sounded resolute afterward that the Celtics would get their act together in Game 7, and there is some reason to believe they will. They’re 6-2 on the road this postseason, and have the fresh memory of beating the defending champion Bucks on their turf in Game 6 in the previous round before winning the series at the Garden. And the road team has already won four times in this wild series.

“We’ve been resilient all year, and this is a different test,’’ said Brown. “Obviously this game hurt to lose on our home floor, but we’ve got to have a short-term memory [loss]. That team over there is hungry. They are experienced. So we’ve got to come out ready to go and almost just forget about last game and come out and have a great mentality.

“This was definitely an ugly game. A lot of stoppages, et cetera. But it is what it is. It’s playoff basketball. We’ve got to come out next game. They forced a Game 7, so now we’ve got to come out and do what we do best.”

Playing Game 7 in Miami shouldn’t faze Brown, who led the Celtics with 25 points in their 93-80 win in Game 5. And he had some outstanding moments in the first half of Game 6, when he and Jayson Tatum combined for 36 of the Celtics’ 46 points before the break.

Can Jaylen Brown and the Celtics respond to their sluggish performance down the stretch in Game 6 with a Game 7 win?Maddie Meyer/Getty

In a stretch of approximately 2½ minutes beginning around the four-minute mark in the second quarter, Brown knocked down two pull-up jumpers, scored on a putback of his own miss, converted a conventional 3-point play, hit two more free throws, and came up with a pair of steals as the Celtics went from trailing, 40-35, to leading, 46-42.

The vibe at that point was one of optimism. The Celtics had the home crowd in their corner and the supposedly fresher legs. But Butler and the Heat had a counterpunch for every Celtics jab. And Brown — and Tatum, too, who finished with 30 points, but on just 12 shots, five in the second half — couldn’t produce in their usual high-volume way.

“I definitely felt like I took care of the ball, found my spots where I could drive, et cetera, and whether the contact was there or not, I just didn’t make enough plays down the stretch,’’ said Brown, who did have five assists, but also four turnovers. “They started doubling, we made some right plays, but definitely got to find more ways to be aggressive next game. It’s a fine line between letting the game come to you and almost being aggressive.”

The Celtics didn’t get much help from their supporting cast other than White. Marcus Smart took a team-high 15 shots, which isn’t what you want, and made just four. Al Horford made one field goal on eight attempts. Grant Williams scored 2 points and yapped at the refs so much you’d think he was the head of NBA officiating. Robert Williams III scored 12 points and provided inspired bursts, but coach Ime Udoka turned away from him in the fourth quarter.

So there’s no way around it: With the Warriors already awaiting the East winner in the Finals, the Celtics let a golden opportunity slip Friday. We’ll know Sunday night whether it’s something they’ll always lament, or one more instance of the Celtics making things tough on themselves before coming through in the end. “If it was easy,’’ mused White afterward, ‘’it wouldn’t be us.”

Brown, and Tatum too, weren’t themselves in the second half Friday. Sunday, to borrow a phrase, the energy had better shift.