"I told Zion at the end of the game that it was by far his best game of the year, if we're taking both ends of the floor," Van Gundy said following New Orleans' 123-101 home win over the Phoenix Suns.
"That was by far his best defense I have seen him play. He covered a lot of ground. He worked really hard."
Williamson's defensive rating against the Suns was 83.3 -- his best this season and the second best of his career. And it comes on the heels of recent private film sessions between Williamson, Van Gundy and Brandon Ingram. Van Gundy said they started following the Pelicans' 14-day road trip that ended with a disappointing loss to the Minnesota Timberwolves a week and a half ago.
Williamson said the sessions have helped on a number of fronts, including his relationship with Ingram and their leadership.
"I think it's great for us and it's great for the team," Williamson told reporters at shootaround Wednesday afternoon. "The team looks on us. If our body language isn't good, they'll start having bad body language. I think if we're always encouraging and always giving our teammates confidence, that can change a lot."
Following the win against the Suns, Ingram said his biggest takeaway from the meetings is becoming self-aware of certain things that Van Gundy is trying to get across to both players.
"I think it's just knowing that every time I go in there, I've probably watched the film two or three times before he tells me," Ingram said. "But just being self-aware of a lot of things so I can speak up a little bit and build a better relationship with [Van Gundy] and build a better relationship with [Williamson], on and off the basketball court.
"Those relationships are important for us to keep going in an upward direction. [Van Gundy] points out everything we can do well and do better and the things we've done well to help our team win."
Part of the coach's message to both players has been making a commitment on both sides of the floor if the Pelicans want to start winning games.
Even though New Orleans lost its previous game to the visiting Sacramento Kings on Monday, Van Gundy still feels like these have been two games of growth on the defensive end, led by the charge of his two star players.
"Games like this, these are important because they show you the possibilities," Van Gundy said following Wednesday's contest. "Obviously, in the second half, we shot the ball well. But in the first half, we didn't. We were 3-for-14. We didn't shoot the ball well. But we had the lead based on our defense.
"We were playing right and getting the right shots. We need to keep this game in our minds and understand all the things that we did to win. You have to know why you win and why you lose. Tonight was the blueprint for us."
Williamson finished with 28 points, seven rebounds and six assists while shooting 12-of-14 from the floor versus the Suns. According to the Elias Sports Bureau, Williamson became the first player in NBA history with multiple games of scoring at least 25 points while shooting above 85% from the field.
He said after the game he knew he was going to be switching onto guards in the Pelicans' pick-and-roll coverages and wanted to be as active as possible when doing so.
"For me to get my teammates some energy, I took that personal so I can just play defense on the guard and get my teammates going in the first quarter," Williamson said. "I know whatever energy we can get, we need. Because we need to run off some wins."
Ingram, who finished with 23 points, six assists and four rebounds on Wednesday, said Williamson was "really good" in his pick-and-roll coverage.
"He was really, really aggressive," Ingram said. "That definitely trickled down to everybody on the team. Our guards started guarding the basketball, and we just tried to emulate what they did."
Williamson's defense has been scrutinized since he entered the league, but he said Wednesday the game is getting "slower and slower" for him as he progresses in his career.
And for the Pelicans, who improved to 8-12 with the win and want to have a shot of getting into the thick of the playoff race, it'll take more efforts like Wednesday's to get back on the right track.
"The thing that I'm most pleased with him and Brandon is we know those guys are going to put up numbers," Van Gundy said. "The question is, are you going to lead teams to wins? That's a hard thing to do.
"You've got to help the other guys and make them better. That's what the best players do. The players that lead teams to winning play both ends of the floor and help their teammates on both ends. Those guys did that tonight. And I think they've been doing that. But Zion's defense took a major step forward tonight."