Donovan Mitchell leaned over to the guy next to him on the bench and said something in his ear. A year and a half ago, the message might have been a little less polite. But it means something very different for Mitchell to give Grayson Allen a piece of his mind these days.

The two young guards saw each other as rivals when Mitchell starred at Louisville and Allen at Duke. They certainly could not see each other someday becoming teammates, let alone friends.

"Definitely not, to be honest," Mitchell says with a laugh.

Now the Rookie of the Year runner-up wants to do everything he can to help the Utah Jazz’s new rookie prepare for his first NBA season. Mitchell took Allen under his wing, working with him in practices and giving him advice on the bench during Summer League, hoping to help his new teammate transition from college to the pro game.

“He’s just giving me some tips for Summer League, an idea of what to expect with the pace of it, all sorts of stuff,” Allen said. “He had a pretty good Summer League last year, so he knows what he’s talking about.”

When Allen shot 4-for-16 from the field in his debut earlier this month at Vivint Smart Home Arena, Mitchell advised Allen he might be better off using his floater in the lane, instead of always challenging bigger, stronger defenders in the paint. Mitchell also gave the rookie tips on running the floor and spacing to the corner on offense.

“It feels really good,” Allen said. “I mean, he wants to help. He genuinely wants to help me. A lot of it was little stuff after plays, after timeouts. When I was coming over he had one little tip for me.

“Most of it was on the floater, or the little bounce pass I could make. Some defensive footwork when guys are trying to call ball screens or being late a few times on help-side defense. Just a bunch of little things that I can improve on that will start to come and will start to be instinctive instead of having to think out there.”

Allen and Mitchell went head-to-head four times during their college careers. Mitchell’s Cardinals won two of those games. Allen’s Blue Devils won the other two.

“We had some great battles,” Allen said.

Allen had a polarizing reputation during his four years at Duke. But the on-court rivalry between he and Mitchell came to a head in January 2017, when the two players got tangled up and Mitchell gave Allen’s face an unsolicited high-five. The incident was caught on camera and memorialized forever online.

What people didn’t see, Mitchell said, was their exchange afterward.

"Everybody has pretty much showed our back and forth," Mitchell said. "But the one thing about Grayson is I always respected him. When people ask me who the toughest guy I had to go against in college basketball, it's him. It's hard when you have all the negative connotations with your name, especially in college. You see it on ESPN and then you've got to go to class and you've got to walk and see everybody on campus—and you still get 30 points a game? That's impressive to me. That's where he got my respect. After that game my sophomore year, I told him how much I respected him."

That respect led to Mitchell endorsing Allen before this year’s NBA Draft.

In the run up to the draft, Mitchell attended a workout in California with Jazz general manager Dennis Lindsey and assistant general manager David Morway.

“It was an excellent workout, a bunch of good players,” Lindsey said. “Grayson got off to a really fast start at the workout.”

And that got Mitchell excited about the possibilities.

“Grayson at 21?” Mitchell wrote to Morway in a text.

A while later, Mitchell made his way over to the Jazz executives to talk some more.

“What do you think?” Lindsey asked him.

“He was a tough competitor, but I’d like to compete with him,” Mitchell responded.

The front-office executives took Mitchell’s opinion in consideration and ultimately drafted Allen with the 21st pick in last month’s draft. And Mitchell, who was at Barclays Center in Brooklyn that night, wasted no time showing everyone how he felt about the pick, embracing his new teammate on camera during a live television interview.

Now having gone from foes to friends, Allen said he intends to lean heavily on his Mitchell for mentorship—and as a measuring stick as he sharpens his game for training camp and his first season in the NBA.

“I have Donovan to go up against every day in practice,” Allen said. “He’s a guy that had an incredible rookie year. If I can measure up against him each day in practice, go against him, that’s just great for me. He’s someone who’s a similar position, a scorer, a similar type player that I can go up against. It’s going to be awesome.”

"Now that we're on the same team,” Mitchell added, “it's going to be a lot of fun."