When Brett Brown entered the playoffs he’d been warned twice, publicly, by his boss that he’d better win now and win big.

He entered having coached his reconstructed starting lineup just 10 times, thanks mainly to chronic tendinitis in the left knee of his best player, Joel Embiid. He entered amid claims that he can’t coach late in games, that he can’t adjust midgame, and that he’d lost the locker room.

Then his No. 3-seed Sixers lost Game 1 of the first round of the playoffs against the No. 6-seed Nets, and, absurdly, #firebrettbrown was trending in Philly.

It’s not trending anymore.

Brown won the next four games. He won close and late, with and without Embiid; he made brilliant in-game adjustments; and he profanely demanded better play from the locker room he’d supposedly lost.

By the time the Sixers took the court for their Game 5 disembowelment of the Nets, 122-100, the Sixers had become an efficient two-way team with defined roles and an obsession with defense as they begin the Eastern Conference semifinals Saturday at No. 2 Toronto.

His biggest move? According to Nets coach Kenny Atkinson, it was blanketing Joe Harris, the NBA’s best three-point shooter this season, by having 34-year-old gunner JJ Redick set up camp inside Harris’ compression shorts.

Redick chased Harris all night, every night. He fought through screens. He dared Harris to cut backdoor — where Harris encountered Embiid or his backup, 7-foot-3 Boban Marjanovic.

“Their defense on Joe Harris really slowed us down,” Atkinson said. “They were top-locking him. He’s kind of our engine.”

Engine? That might seem like an exaggeration for a fourth-year player who, before this season, started 26 NBA games, then averaged 13.7 points, third on the team. But Harris led the league with a 47.4 percentage on three-point shots this season, and he’d scorched the Sixers at 55.6 percent in their four regular-season meetings.

That ended. He shot 19 percent in the five-game series, and just 5.9 percent after Game 1. It’s even worse than it sounds.

Harris made 3 of 4 threes in the first seven minutes of Game 1. He didn’t make another until just under six minutes remained in Game 5, a span of about 203 minutes, or the equivalent of more than four entire games. He didn’t connect at all in Games 2, 3, and 4, going 0-for-12.

“Early on, I struggled adjusting to how they defended me,” Harris admitted. “A lot of my action is coming off screens and trying to move without the ball. They did a good job taking away any clean looks I might have gotten from three, forcing me to go down in the paint, forcing me down off of screens.”

He credited Redick, who usually is a defensive liability.

“The way that he defended, he didn’t get enough credit,” Harris said. “He made things tough for me all series long. He’s a great position defender.”

That isn’t to say Harris was never open. When he did see daylight, he was too rattled to capitalize.

“As the series wore on, I was better at adjusting to it. But by then I wasn’t able to find a rhythm or get anything going offensively,” Harris said. “I just wasn’t able to knock them down.”

Knocking guys down became a theme. The Sixers led by a point at halftime of Game 2, when Brown decided it was time for the gloves to come off.

He benched backup point guard T.J. McConnell and gave swingman James Ennis more minutes. When Ben Simmons sat, Brown handed ballhandling duties to forwards Jimmy Butler and Tobias Harris. The team that used the pick-and-roll second-least in the NBA, behind only Golden State, turned to Jimmy Buckets and Toby.

The Sixers responded with a record-tying third quarter and took control of the series.

“That was a big turning point, the 51-point third quarter,” said Jarrett Allen, the Nets’ skinny center, who was twice flagrantly fouled by Embiid, who is about 50 pounds heavier. “That gave them confidence.”

They were inspired.

Brown seldom challenges his charges, but then, in his six Process-driven seasons. he seldom had charges worthy of challenge. After watching six quarters of lousy defense to start the playoffs, Brown laid into the Sixers with a halftime rant for the ages.

He has won 103 games the last two seasons, has won two of the three postseason series he’s been in, and he has done it while usually unsure if Embiid will play.

Is Brown proud of his performance so far? Does he feel vindicated?

“It’s the world we live in," he told me. "I do know this: These players play for each other.

"And they let me coach them.”