Toronto Raptors president Masai Ujiri said Monday night that his relationship with ex-coach Dwane Casey has significantly improved, but there is "still plenty of work to be done" for him to get to the same place with former franchise icon DeMar DeRozan.

Ujiri fired Casey and then traded DeRozan for Kawhi Leonard two years ago.

"It's not easy," Ujiri said of such decisions in an interview with TNT's Ernie Johnson that aired on the NBA's Twitter account. "If you have that human part of you, you feel it in your heart.

"I will never forget, I will never, ever forget having to do that with Coach Casey and walking to his office, waking up that morning. Many times I wanted to move it and change it or think that you're not making the right decision. It was incredibly hard, because Casey is an incredible person, and so great to work with. ... DeMar, I was in the hotel in Kenya, and I walked around that hotel at 4 a.m., 5 a.m., for a couple hours, trying to gather up enough strength and courage to make this phone call. I will never forget it.

"With Casey, it has gotten so much better now with his family and him. With DeMar there is still plenty of work to be done. But, by the grace of God, it will all get better. We have to continue to make these decisions that are tough. But that's the business of basketball, and the position that we are in."

It was a tumultuous 14 months from the end of Toronto's sweep by the Cleveland Cavaliers in the 2018 Eastern Conference semifinals until Leonard left the Raptors and joined the LA Clippers as a free agent in July 2019. In between, Ujiri fired Casey, who had been Toronto's coach for seven seasons, traded DeRozan, who had been the face of the franchise for nine seasons, and then won the Raptors' first championship in Leonard's lone season with the franchise. Leonard would leave a few weeks later as a free agent.

That combination of events led to a roller coaster of emotions -- something Ujiri said is simply part of the job.

"I always say that the two hardest things in our world, in our business, is trading a player and then when a player leaves, if a player leaves in free agency," Ujiri said. "And it's hard on both sides. When a player is traded, it is hard on the player side, and when a player leaves, like us [with Leonard last summer], it is hard on that side. I've experienced all of it, from wonderful people.

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"It sometimes puts a strain on relationships, as we saw with DeMar. People don't know even with [when we traded] Rudy Gay, I was close to Rudy. Incredible kid. Incredible kid with DeMar, where you build and you're trying to preach a culture of good, of trust, of being with people, and then you have to make this decision [to trade him].

"With Kawhi, we just built a relationship where we trusted each other, and that friendship has evolved even bigger after he left, and I'm proud of that. I support him with everything he does as a human being, and his family, and you move on. You've got to move on to the next ..."

For both Ujiri and the NBA, it's difficult to know, from a basketball standpoint, when "the next" will be. The league, like the rest of the sports world, remains shut down because of the coronavirus pandemic -- just as it has been since Utah Jazz center Rudy Gobert tested positive for the virus just before tipoff of a game in Oklahoma City on March 11, with the league suspending operations indefinitely a short time later.

But Ujiri said NBA commissioner Adam Silver was thinking about the potential ramifications of the coronavirus on both the NBA and society well ahead of having to shut down. He said he was at a meeting at NBA headquarters in New York a few weeks earlier for an NBA Africa board meeting when, after the meeting ended, Silver began to speak about it.

"After the meeting, Adam started talking about this virus," Ujiri said. "And the way he talked about it, and how passionate he was about where this thing was going, it was incredible to see. In my mind, I have told this to my wife and now I am telling the whole world this, I can't believe it, and I said, 'Why is he being so dramatic about this?' You think like that, you know? This is how serious this is, and this is how we have to pay attention to this. We have to stay home and social distance. ... He had the foresight. He had the vision.

"It's not only him starting this for the league, or other leagues, it opened [the problem] clearly [for the world]. That's leadership."

Ujiri said that he and other members of NBA front offices "have tons of ideas" about how the sport could eventually return, but that he trusts Silver's leadership to find the right way. And, he added, he expects the NBA to come back "in some kind of way" from its hiatus.

"I know with all the input his leadership team with the NBA, and how he directs it, we will come up with something great," Ujiri said. "He's taking all our input. I am confident that we'll get back playing in some kind of way. We miss the game, man. We miss sports. We miss the game."

If the NBA is able to return and finish its season, Toronto will be in the thick of the East playoff picture. The Raptors have exceeded virtually all outside expectations, posting a 46-18 record -- second best in the East -- with Pascal Siakam emerging as an All-Star to pair with guard Kyle Lowry. Coach Nick Nurse is the favorite to earn Coach of the Year honors.

Ujiri said that the organization's belief in itself, as well as its collective determination to mount a defense of its first championship, were catalysts for an impressive season.

"Honestly, from the inside you try to keep your mouth shut," Ujiri said with a laugh when asked if he was surprised by Toronto's success. "You know how we are in the NBA, with karma, and you just want to keep going. But honestly, with our coaching staff, with the group we had, and somehow you hope your talent rises, the young players rise and players step up with Kawhi leaving, and that's all they did. They stepped up and they were better. They fought, and they were innovative.

"I think Coach has an incredible mind with how he thinks the game, the rise of Pascal, and how about Kyle Lowry? It's almost reversed. ... It's basically the older he becomes, the better he becomes. And then all the other guys -- Fred [VanVleet] has become a wonderful guard in this league, Norman Powell has stepped up. The team has great courage and they fight, and yes, there is something to prove, almost, to the whole world, but we're on a stage where we took pride in defending the title, and I'm proud of these guys for really doing that."