NBA legend Michael Jordan sat in tennis legend Roger Federer’s box Tuesday night, making his first appearance at the U.S. Open after the two greats collaborated on a new shoe.

The Swiss Maestro debuted the shoe patterned after an Air Jordan model in his opening-night 6-3, 6-4, 7-6, straight-set victory over Aussie Marinko Matosevic. Oh, is the karma in the air for Federer to regain the Open throne again after a five-year drought.

Jordan, owner of the newly renamed Charlotte Hornets, told The Post as he entered the stadium: “I love the shoe.’’

Jordan and Federer met for the first time Monday. Asked about Federer’s chances to win his sixth Open, Jordan said, “I think he’s got a good chance. That’s why I’m here. I hope he can [win it].’’

Federer, 33, was genuinely moved Jordan was on hand.

“It is just amazing having Michael here,’’ Federer said on court after the match.

Later, Federer said Jordan was his sports idol, though he didn’t have a jersey.

“He was my hero of all sports,’’ Federer said. “I had Jordan as my all-sports idol. [Stefan] Edberg and [Boris] Becker were my tennis idols. Every Sunday they had big NBA highlights. That’s what inspired me.’’

Jordan used to dabble in tennis but has become a bigger golfer.

“He looks so smooth,’’ Jordan told Mary Fernandez on the ESPN telecast. “I’ve seen a lot of him on TV, but you don’t understand how fundamental and smooth he can make it look. It’s fascinating how smooth. He makes the shoes look a lot better.”

Said Federer: “He was one of the smoothest movers out there.’’

Federer’s new Nike shoe is the Zoom Vapor AJ3.

“He had a lot of input in it,’’ Jordan said. “One of my shoes was his favorite — the 3. He took it to heart.’’

On one attempted leaping overhead, he didn’t look like Air Federer, battering it out in the second set. But he coverted a jump overhead in the match-ending tiebreaker.

“I did miss it badly, I couldn’t get enough air on,’’ Federer said jokingly.

Asked about the Ashe Stadium atmosphere, Jordan said, “It’s a little quieter than Madison Square Garden, but these are tennis enthusiasts, fans who understand the game and give you the boost of energy. Roger was saying that [Monday] night. I was saying the same thing. The Garden was the Mecca, and playing at the Garden, they appreciated the way you play the game. He said it’s the same way here in tennis.’’

Jordan declined to discuss basketball. Asked by about Carmelo Anthony’s and LeBron James’ free-agent decisions,

Jordan said, “It’s their decisions,” then darted into Ashe Stadium.