Michael Porter Jr. aced one of the toughest assignments in the NBA on Friday and looked like a challenge to guard himself on Saturday.

While the Nuggets forward didn’t start many possessions as the primary defender on Luka Doncic in Denver’s 125-114 win in both teams’ In-Season Tournament opener Friday at Ball Arena, the Mavericks star regularly sought out Porter. The Nuggets’ defensive scheme has long included switching all screens not involving Nikola Jokic, so all Doncic needed to do was call for a screen from Derrick Jones Jr. or whoever else Porter was guarding to get his preferred matchup. It didn’t go the way Doncic hoped.

“He was really locked into the gameplan, switching onto guys like Luka and Kyrie (Irving) and just doing the best job he can defensively,” Nuggets coach Michael Malone said after Friday’s game.

“Michael had his fingerprints all over the win tonight.”

Denver’s starting small forward caught fire in the second half of Saturday’s 123-101 win over the Bulls. He finished with 27 points on 16 shots thanks to a 5-for-10 mark from 3-point range. In the back-to-back weekend games, Porter went 9 for 18 from 3-point range.

On the defensive end Saturday, the Bulls tried something similar early on Saturday night. Porter started most defensive possessions matched up with former teammate Torrey Craig, and Chicago put Porter in a couple of screens early but wasn’t as deliberate about it as Dallas was the night before.

Porter said his biggest priority while defending Doncic, who averaged 33.8 points, 10.5 rebounds and 9.8 assists in the Mavericks’ first four games, was preventing him from getting to his step-back 3-pointer. Doncic went to that shot the first time he got the switch. Porter contested the shot, which clanged off the bang of the rim, and beat Doncic down the court for a transition dunk. A couple of minutes later, Porter’s long arms forced Doncic to reconsider a similar shot and give up the ball. Later in the first quarter, Doncic tried his hand at driving past Porter. That didn’t work, either. Porter stayed on Doncic’s hip with a hand in his face and forced one of Doncic’s nine turnovers on the night.

“He’s a great player, and being 6-(foot)-8 kind of at the point guard position, he’s able to seek matchups and use his height and his strength against a lot of players,” Porter said Friday. “All you can do is make it tough on a player like that. You just got to compete and take on the challenge. That’s what we all did tonight.”

Nobody did it better than Porter, who was awarded the team’s defensive player of the game award. Kentavious Caldwell-Pope had won the award in each of Denver’s four previous wins this season.

Doncic tried something new in the second quarter. He called for one screen to get to Porter before calling for a second, this one involving Jokic. Since the Nuggets don’t want their star center switching onto guys like Doncic, Porter had to fight through a screen. Then, he poked the ball off Doncic’s leg and out of bounds, creating another turnover. While he wasn’t credited with a steal, he did record two blocks on the night.

“Defensively, he had a couple of deflections, a couple kind of chase blocks,” Jokic said after the first of Denver’s two weekend games.

“He was guarding one-on-one, so he was really good tonight.”

Porter got another easy bucket before halftime leaking out after another one of Doncic’s errant step-back 3s, and he closed the first half by forcing Doncic into a tough pass that Caldwell-Pope stole.

After halftime, Doncic tried to back down Porter before pulling up at the free throw line. Doncic has long been able to draw fouls on similar plays, but Porter put his hands in the air right when Doncic started going up.

“He’s so versatile, can go both ways,” Porter said. “Then, when he starts driving, he’s so crafty drawing fouls. You got to put your hands up. I just tried to make it tough on him. Really, that’s all you can do.”

After forcing another Doncic turnover and missed shot, Porter’s final defensive play came in an 11-point game with four minutes left. Doncic again tried to get to his step-back 3 but couldn’t connect. The Mavericks star still finished with a game-high 34 points with 10 rebounds and eight assists, but he only made a couple of buckets when defended by Porter, who came a long way since Monday. Earlier in the week, Malone opted to close the game against the Utah with Christian Braun in Porter’s place.

“He bought into playing defense, to trying and realizing that if he doesn’t, he’s not going to be in there at the end of the games. Michael Porter hates coming out at the end of the game, so he realizes ‘OK, coach will play me if I’m trying.’ He’s not going to be perfect,” Malone said. “None of our guys are perfect, but what Michael has shown me is that he cares. He’s trying. He cares, and he’s giving it the best effort that he can. Tonight was a hell of a performance from him on both ends.”

Porter scored a season-high 24 points on 10 of 18 shooting. He made four of eight attempts from 3-point range and grabbed five of his nine rebounds on the offensive glass, but the defense was the most impressive part of his night. The improvements on the defensive end are a byproduct of better health and extra experience, he said. He’s nearly two years removed from his third back surgery, though he’s still playing through a bothersome ankle. The 25-year-old said he started the season around 50 percent healthy. Now, he’s closer to 75 percent. The experience that came with more high-stakes minutes has also helped him start to shed his reputation as a defender who can be exploited.

“Part of it is experience, playing against certain players, just being out there on the floor more. Over the years, I think you just naturally get better, and then, yeah, part of it has to do with how I feel physically. My ankle doesn’t feel 100 percent, but I just feel like I’ve kind of figured out how I should be playing guys on defense in iso situations. That’s not crowding them. It’s using my length,” Porter said.

“It’s just something you get better with over time. It’s something I’ve had to get better with to be on this team and to fill the role that I need to fill on this team.”

NUGGETS 123, BULLS 101

What happened: Denver overcame a slow start to improve to 6-1 on the season. The Nuggets made just one of their eight 3-point attempts in the first quarter but managed to start the second quarter with a one-point lead. Chicago responded and to take a 53-51 advantage at halftime. An 18-2 run to start the third quarter allowed the Nuggets to regain the lead in the first minute of the third. Denver would go on to lead by as many as 18 points in the third but settled for a 12-point edge to start the fourth. The starters stretched the lead to 20 in the final minutes before the bench closed it out.

What went right: Nikola Jokic decided to take over the third quarter. After finishing the first half with 11 points, five rebounds and three assists, Jokic added 13 points, nine rebounds and three more assists in the third quarter alone. That helped Denver turn a two-point deficit into a 16-point lead when he checked out for the final 1:33 of the third quarter. He finished with 28 points, 16 rebounds, nine assists and three steals.

What went wrong: Jamal Murray left the court early in the second quarter and did not return with what the team called right hamstring tightness. Murray was listed as probable for this weekend’s game with a right quadriceps contusion. Without Murray in the second half, the Nuggets used Reggie Jackson with the starting unit and Collin Gillespie with the second unit.

Highlight of the night: Gillespie got on the board Saturday. After missing all of last season with a serious leg injury, Gillespie scored the first two points of his NBA career in the third quarter after Michael Porter Jr. found him with an impressive pass for an open layup. A couple of minutes later, Gillespie hit Christian Braun for a dunk and hit his first 3-pointer in the final minutes.

Up next: The Nuggets have Sunday off before welcoming Zion Williamson and the New Orleans Pelicans to Ball Arena on Monday.