Down 3-1 and missing their injured star, the Boston Celtics weren’t ready to fold just yet.

With Jayson Tatum sidelined for the postseason — and likely next season — due to a torn Achilles, Boston found unexpected heroes in Derrick White and Luke Kornet to overpower the New York Knicks 127-102 on Wednesday night at TD Garden.

White exploded for 34 points, hitting 7-of-13 from beyond the arc, while Kornet came off the bench to deliver a defensive clinic with 7 blocks, 10 points, and 9 rebounds on perfect shooting.

The Celtics trimmed the series deficit to 3-2 and will now head to New York for a critical Game 6 on Friday.

Jaylen Brown added 26 points, 12 assists, and 8 rebounds in a near triple-double effort, with Payton Pritchard and Jrue Holiday combining for 31 points.

Boston broke away in the third quarter with an 11-0 run, sparked by White’s sharp shooting and Pritchard’s timely three-pointers.

For the Knicks, Jalen Brunson put up 22 points but fouled out midway through the fourth quarter, leaving a scoring void New York couldn’t fill.

Josh Hart led the team with 24 points and 7 rebounds, while Karl-Anthony Towns chipped in 19.

Tensions ran high in a physical contest, punctuated by hard fouls in the first quarter. Hart took an elbow from Kornet that left him bloodied, and earlier, Brown was dropped by an uncalled elbow from Brunson.

The officials reviewed both sequences but ruled common basketball moves.

Despite Kristaps Porziņģis scoring just one point, Kornet’s energy and rim protection neutralised New York’s frontcourt, with OG Anunoby, Mikal Bridges, and Mitchell Robinson all held to single digits.

Now, with their backs still against the wall, the Celtics head to Madison Square Garden looking to push this bruising series to a decisive Game 7.