Before D’Angelo Russell canceled a meeting with the Sixers last weekend, raising eyebrows, the Ohio State guard quietly worked out for the Knicks on June 11 in Westchester, The Post has learned.

Russell, after the Knicks meeting, didn’t show up for the Sixers workout reportedly because he got sick. But he was back East Wednesday to work out for the forever-rebuilding Philly franchise, which may hold the key to Phil Jackson’s draft fortunes.

If Karl-Anthony Towns, Jahlil Okafor and Russell are off the board at No. 4 in the June 25 NBA Draft, the Knicks may try harder to trade down and accumulate an extra asset. They have three trade exceptions to use to engineer a trade down to the No. 7-to-14 range and still land a much-coveted big man such as Willie Cauley-Stein or Frank Kaminsky, who will work out for the team Thursday.

The Post reported last week the Sixers have been set on Russell at No. 3 for a while. Sixers head coach Brett Brown is a Rick Pitino disciple, and the Louisville coach is enamored of the crafty Russell, who grew up in Louisville.

However, an enormous publicity campaign has been waged in the past five days by agent Andy Miller for Spanish league 7-footer Kristaps Porzingis, who had a stirring open workout in Las Vegas on Friday.

Prominent draft site Draftexpress.com has penciled in Porzingis to the Sixers at No. 3. With the news that injured center Joel Embid may not be ready for the start of next season, the Sixers may prefer another big man and eschew the point-guard position.

That means Russell would fall to the Knicks.

However, a league source insists the Sixers taking Porzingis over Russell is a reach and they are after the best available player regardless of position.

“If you’re basing taking him because of last week’s workout, you should be fired,’’ the league source said.

Porzingis is a polarizing player because he put up minimal statistics for Seville, is just 19 years old and his body is not NBA-ready. He’s listed at 220 pounds, and some feel he’s two seasons away from contributing.

However, Tim Shea, a former Knicks scout in Europe who now tutors coaches in Spain, says Porzingis can become a player similar to Bob McAdoo, the original sweet-shooting 7-footer, who played for several teams, including the Knicks and Nets.

“He plays within himself, plays for the team and has gotten better every year since I’ve seen him,’’ Shea told The Post. “He loves to play, loves the game, puts the work in and is well-liked by teammates because he puts team first and has a good character. I wouldn’t be obsessed with his numbers over here.’’

Jackson, coach Derek Fisher and personnel director Mark Warkentien attended the Porzingis workout. Most of the lottery teams interviewed Porzingis afterward, including the Knicks.

Even though Carmelo Anthony is said to be intrigued by Porzingis, players such as Russell, Justise Winslow, Cauley-Stein and Emmanuel Mudiay would give the Knicks a bigger boost the next two seasons.

After Russell’s workout for the Lakers 10 days ago, he told reporters he could be the next Stephen Curry, the reigning MVP and NBA champion.

“I just try to really model my game after Steph Curry,’’ Russell said. “He didn’t come into the league playing the way he’s playing now. It took some time. The player that he’s developed to be — I see a great resemblance. His ball-handling is off the charts. His shot selection I can say is kind of similar to mine. But like I said, his work ethic to get him where he’s at I would say is similar to mine also.’’

Despite speculation Russell is trying to avoid the Sixers, he realizes he will be drafted by a losing team regardless. The Knicks were 17-65 last season.

“Most of these teams are in the same situation to pick the top guys because they didn’t win,’’ Russell said. “So I definitely know they want a guy to come in and help them win games. That’s my main focus. If that’s going to the No. 1 pick or third, fourth, fifth — whatever pick it is — it’s going to a team to help them win.’’