The friendship between Josh Hart and Donovan Mitchell has come a long way from the Villanova practice gym.

They were in the 2017 NBA draft class together, took part in some of the same draft workouts, and have spent large portions of their offseasons training in Miami.

Now they are in each other’s way, as Hart’s Knicks and Mitchell’s Cavaliers prepare to meet in an opening-round, best-of-seven playoff series starting Saturday in Cleveland.

“I was on FaceTime with him earlier [today]. We have the same barber, have to make sure the barber was there so I can get a fresh cut,” Hart said with a smile after practice Wednesday. “It’s exciting because that’s someone I’ve known for the last seven years. Someone who I’ve watched grow in the league. Someone who has a great personality, a high character kid. So it’ll be fun. We play video games together. We talk trash. Hang out.”

They first met when Hart was playing for Villanova and Mitchell would come by to work out.

Mitchell’s close friend Eric Paschall was a teammate of Hart’s in college.

Their bond only strengthened as they made their way in the NBA.

Now they will be enemies, at least on the court.

Hart may defend Mitchell more than any other Knick, although coach Tom Thibodeau made it clear he isn’t counting on any one player to slow down the four-time All-Star.

Mitchell is coming off a fantastic season in which he set career-highs in scoring (28.3) and field-goal percentage (48.4).

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He averaged 31.8 points in four games against the Knicks.

Hart, however, only appeared in one of those after he was acquired in a deadline deal from the Trail Blazers.

“As a competitor, if you’re not excited for these matchups, for these games, I think you’re kind of in the wrong sport,” Hart said. “When you’re playing against the Donovan Mitchells in the league, someone who is a good scorer on all three levels, someone who is shooting almost 50 percent from the field, 38 from 3, high-80s from the [free-throw] line, he’s getting it done from everywhere on the court. So definitely getting excited for someone like that.

“You’ve got to be ready because there are going to be times when you do everything right defensively and he makes a tough shot. And you’ve got to be ready for that and not let that discourage you.”

Saturday will be Hart’s introduction to the postseason in his sixth season in the league.

The Knicks were already a good team prior to his arrival, but he at least partly took them to another level, similar to the effect the addition of Derrick Rose had two years ago.

The Knicks went 17-8 with Hart, highlighted by a nine-game winning streak upon his arrival.

He didn’t start, but made an immediate impact as an essential ball-moving, defensive-minded, hustling contributor.

In those 25 games, he averaged 10.2 points, 7.0 rebounds, 3.6 assists and shot a through-the-roof 51.9 percent from 3-point range.

The Knicks outscored the opposition by 11.9 points per 100 possessions when Hart was on the floor.

His 123.1 offensive rating was the best on the team.

“Josh has fit like a glove,” Thibodeau said. “Just a good, all-around player. There’s no agenda, other than winning. Provided whatever the team needs, whether it’s defense, rebounding, pushing of the ball, big 3s. … That’s what I define as a playmaker. What does the game need, he provides.”

Hart was initially thrilled when he was traded to the Knicks, getting to return to his East Coast roots and reunite with former Villanova teammate Jalen Brunson.

But there was some apprehension, too, not only switching teams midseason for the second time in his career, but with a pregnant wife, to boot.

But right away, he felt at ease.

Thibodeau entrusted him from the outset, using Hart to finish games.

He became a pivotal player, and he will be critical for the Knicks to pull the upset in this series, Hart will almost certainly have to be a focal point, particularly on defense.

“I’m going to push my body as much as I can,” Hart said. “I try to play hard on every possession. Playoff time, I’m going to have to find another gear to get to.”