The New York Knicks weren’t supposed to be down 22 points in the fourth quarter in Game 1 of the Eastern Conference Finals at home in Madison Square Garden, especially coming off a week’s rest — and while the Cleveland Cavaliers had just won a Game 7 against the Detroit Pistons less than 48 hours earlier.

But with 7:48 remaining in the game, the Cavaliers — 6.5-point underdogs entering the game — had a 93-71 lead. And one bettor was sweating through a series of five- and six-figure wagers on the Knicks.

A bettor at BetMGM had wagered $775,000 on a series of ladder bets on the Knicks to cover at various numbers before the game, ranging from Knicks -2.5 to Knicks -6.5. Here was the full range of wagers:

• $70,000 on Knicks -6.5 (-120)

• $95,000 on Knicks -5.5 (-140)

• $185,000 on Knicks -4.5 (-160)

• $350,000 on Knicks -3.5 (-185)

• $75,000 on Knicks -2.5 (-210)

Realistically, the bettor’s only chance to win any of these wagers was for the game to go to overtime — and that’s exactly what happened, as the Knicks staged a furious rally from that 22-point deficit to force overtime. And New York never trailed in OT, en route to a stunning 115-104 win.

The Knicks had money-line odds of as high as 80-1 at one point in the fourth quarter at DraftKings.

New York ended up covering every one of the five wagers for this bettor — who has been making ladder bets throughout the playoffs and is up on his reported wagers — and Cavs +6.5 will go down in history as an all-time bad beat for spread bettors.