The Knicks mopped the floor with the Sixers the last time they met in the playoffs. Three decades ago.

It could have been the start of something big. Maybe it should have been. Crazy as it sounds, when Game 1 between the 76ers and New York Knicks tips off Saturday at Madison Square Garden, it will mark the first time the teams have faced each other in the playoffs in 35 years. And the final image of that series was the sort of moment from which blood feuds are born. Just not in this case.

Doesn’t feel right, does it? Philly-New York is supposed to be a bitter rivalry, at least around here. Usually is. Eagles-Giants, Phillies-Mets, Flyers-Rangers — those games all matter a little more. For Sixers-Knicks, though, the timing was never right.

When the Sixers were good, the Knicks weren’t. When the Knicks were good — and hey, it had been a while until Jalen Brunson showed up — the Sixers weren’t. In that context, it’s understandable that what happened on May 2, 1989, remains mostly a distant memory and isn’t considered the kind of anecdote that, if you mention it, immediately raises a Philly fan’s blood temperature to 212 degrees Fahrenheit.

A refresher, in case you don’t remember or have never looked back so far: That night, the Knicks completed a three-games-to-none series victory over the Sixers in the Eastern Conference quarterfinals, beating them in overtime at the Spectrum, 116-115. And after the horn blared and while Charles Barkley lay supine at midcourt, distraught and disbelieving that his team had lost, the Knicks — Patrick Ewing, Charles Oakley, Mark Jackson, all of the Knicks — grabbed a dust mop from under one of the baskets and started pushing it across the court.

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A sweep. Get it?

“It kind of rankled us a little bit,” John Nash, the Sixers’ general manager then, said Thursday.

Can’t blame them. It wasn’t as if the Knicks demolished the Sixers. They outscored them by just eight points in the series. New York’s one-point win in Game 3 came three days after a one-point win in Game 2. And Barkley was the series’ best player, putting up 27 points and pulling down nearly 12 rebounds a game and shooting 64% from the field.

“Charles was great, and that’s why we should have won,” former Sixers coach Jim Lynam said. “Patrick was really good. Charles was better.”

The Knicks were talented and deeper, though, with Rick Pitino, in his second season as head coach, pushing them to play an up-tempo style even with the plodding Ewing as the franchise centerpiece. They went 52-30 to win the Atlantic Division and were the NBA’s third-highest scoring team, and the difference against the Sixers, the factor that swung the series, was the teams’ backcourts. Jackson, Rod Strickland, and Gerald Wilkins outplayed Maurice Cheeks and rookie Hersey Hawkins, who missed 21 of his 24 shots.

The games themselves were tense and physical, on the floor and elsewhere. Hundreds of Knicks fans traveled to the Spectrum for Game 3. At times, they chanted, “SWEEP! SWEEP!” Several fights broke out. Trash talk flew back and forth between players. New York’s didn’t mind. Strutting came naturally to them. “They had been talking, saying negative things,” Ewing said of the Sixers. “So I wanted to rub it in a little bit.”

The Knicks also knew they’d have home-court advantage in the second round, which they presumed would give them an easy path to the conference finals. Their opponent would turn out to be the Chicago Bulls, who beat the Cleveland Cavaliers in five games only because Michael Jordan hit his famous hang-at-the-foul-line buzzer-beater over Craig Ehlo. But that Bulls-Cavs series was still tied 1-1 when the Knicks finished off the Sixers, so why not celebrate themselves? What did they know?

“I’m going to chalk that one up to being very inexperienced and young,” longtime NBA guard Trent Tucker, who won Game 2 with a late three-pointer and at 29, was the oldest player on New York, said Thursday. “We weren’t very mature in understanding that wasn’t something you were supposed to do.”

The public reaction was predictable. In the New York Times, as one example, columnist Ira Berkow wrote, “It was tacky, as they say in one part of town; it was in your face, as they say in another. It was everything but proper.” Ahead of the teams’ first regular-season rematch, a newspaper article that showed a photograph of the Knicks’ sweeping the floor was taped inside the locker of every Sixers player, though Barkley dismissed the incident’s significance: “We’ve got too many important things happening in our lives to worry about a broom.”

That ‘89 postseason marked a transition point for each team, though neither franchise’s future unfolded quite the way it would have liked. After the Knicks lost to Chicago in six games, Pitino and general manager Al Bianchi fell into a fierce conflict over the team’s direction. Pitino wanted to continue to play fast, but the front office, for the sake of building around Ewing, preferred a slower, halfcourt-oriented approach. Pitino became the head coach at Kentucky, and it took two years of mediocrity before the Knicks found the right replacement for him in Pat Riley.

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As for the Sixers, Cheeks averaged 17.7 points and 13 assists in the series, but Game 3 marked the last time he played for the Sixers — the last time that any member of their 1982-83 championship club played for them. The following August, they traded Cheeks to the San Antonio Spurs in a five-player deal that included Johnny Dawkins, who would be their new point guard. The last connection to those terrific teams of the late 1970s and early 1980s had been cut.

“When you talk about a consummate pro and a true champion,” Tucker said in a phone interview, “he knew exactly how to run a team. The big stars got the billing, but the glue to those teams was Maurice Cheeks.”

That background goes a long way to accounting for why the mop stunt hasn’t had the staying power, the lasting bitterness, that another graceless gesture might. Despite their high hopes, both teams ran into the NBA’s dual dynasties of that period. Everything else in the league was a secondary story to the battles between the Bad Boy Detroit Pistons and Jordan’s Bulls. Plus, if anyone from the ‘88-’89 Sixers harbored a grudge, he kept it to himself. Even Lynam, when reached by phone Thursday, shrugged off the Knicks’ antics.

“It’s about winning the game,” he said. “If they want to go do a handstand on Broad Street, what’s that got to do with me?”