Friday’s Sweet 16 showdown between second-seeded Duke and third-seeded Michigan State marks the eighth meeting in the rivalry between two of college basketball’s A-list coaches: Mike Krzyzewski and Tom Izzo.

Krzyzewski is 6-1 against Izzo, and the respect between the two has only increased in every game since the pair first met when Izzo was a Spartan assistant. That meeting came when the Blue Devils beat Michigan State in the second round of the 1994 NCAA Tournament, Izzo’s 11th year as an assistant in East Lansing and two years before he was named head coach.

“They hate each other,” joked Jud Heathcote, Izzo’s predecessor at Michigan State.

Krzyzewski describes Izzo as a “very close friend,” adding that “Tom’s jokes are funnier than Jud’s.” But the Izzo-Krzyzewski relationship nearly did not have the chance to grow the way it has in the 18 years that they have both been head coaches.

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Izzo did not have any head coaching experience before Michigan State hired him, but Heathcote strongly supported his longtime assistant’s candidacy because of the growth he saw in him during their time together.

“I worked hard to get Tom the job when I retired. I believed in the continuity and that he deserved the job,” Heathcote, now 85 years old, said. “If I hadn’t gone to bat for him, he wouldn’t have gotten the job because they looked for somebody who had head coaching experience, and there was great pressure there to hire a black coach.”

Izzo has validated Heathcote’s support, going to the Sweet 16 in 11 of his 18 seasons in charge. That’s three fewer than Krzyzewski in that span, and Duke’s skipper has one more national title in that period and three more overall.

“I admire what Michigan State did a long time ago, saying this guy can take over for Jud because Jud had great success there,” Krzyzewski said. “Tom has continued that and probably taken it up a little bit more.”

The first meeting between Izzo and Krzyzewski as head coaches came in the 1998-99 season when the Blue Devils won by six in non-conference play. They met again in that year’s Final Four, another six-point victory for Duke.

“There’s no question that if you look at the NCAA Tournament and what’s been done. Nobody’s Duke because Duke is Duke,” Izzo said at his press conference Monday. “But we’re one of the closest things to it as far as consistency.”

Krzyzewski’s lone loss to Michigan State was a 10-point defeat in the Sweet 16 of the 2005 NCAA Tournament. Duke had beaten the Spartans earlier in the year when J.J. Redick scored 29 points, but a stingy Michigan State defense held Redick to 4-of-14 shooting and 14 points in the second meeting.

The last time they played, Krzyzewski won his record-breaking 903rd game at Madison Square Garden.

The way Izzo has handled his wins and defeats has only increased Krzyzewski’s respect for his counterpart.

“He’s a coach’s coach. He’s a guy’s guy. With all the success, he’s a humble guy,” Krzyzewski said. “There’s not a thing I don’t like about Tom, and he’s become a good friend over the years.”

And none of that will change even though only one of the longtime friends’ two teams will be able to advance to this year’s Elite Eight.

“He appreciates that we’re going to compete, and they’re going to compete,” Izzo said. “It’s going to be war.”

Correction: An original version of this article said Tom Izzo reached the Sweet 16 16 times. The Chronicle regrets this error.