CHAMPAIGN – Just three years ago, the world was turned upside down, and it was hard to tell how long it would last.

A former young Chicago suburban prep superstar who served his apprenticeship at Duke, Chris Collins guided Northwestern to its first NCAA Tournament appearance in school history. After placing fifth in the Big Ten Conference, the Wildcats won their first-round game before a heartbreaking loss in the round of 32. Nonetheless, the school appeared poised to build on the momentum for the breakthrough moment, and it had the feeling of the miracles Pat Fitzgerald put together with the Northwestern football program.

Meanwhile, there was no quick fix for the Illini, who were still trying to find the magic from those days more than a decade ago when the Illini were on top of the Big Ten. For the second straight time, a lack of performance led to the firing of the coaching staff, something that hadn’t happened here in our lifetime. Brad Underwood brought his own tournament history, but this turned out to be more than just a weekend fixer-upper.

He lost 14 games in the Big Ten in his first year and another 13 in the second year, when the Illini set a school record with 21 losses. Following a roster overhaul and recruiting spearheaded by assistant Orlando Antigua, the Illini have resurfaced on solid footing. After the 74-66 victory at Northwestern Thursday, the Illini have more Big Ten wins than any time in the last 11 years. (OK, so the Big Ten season is longer now, but the Illini still have three games remaining.)

No longer does Underwood have to reference the past, unless he’s talking about the process of bringing the Illini back to relevancy. He referred to it as growth. It’s appropriate, because these Illini have grown on the fans so much that orange and blue took control of the arena in Evanston Thursday and will likely make a strong showing now that the Big Ten Tournament is back in the Midwest.

“It’s growth,’’ Underwood said. “We’re getting there.’’

With a mixture of Chicago, East Coast and international players on the roster, Underwood built his team unlike previous coaches, who leaned heavily on local instate recruits. Times have changed, and Antigua’s reach in New York City plus the international scene led Illinois to a more world-wide approach.

The Illini program is on solid footing, Underwood said, yet there’s plenty of room to grow and keep climbing the rungs in college basketball.

“It’s a process,’’ Underwood said. “There’s no substitute for building. You don’t just turn around one day and have a house built. You have to start with a foundation and dig a hole. That’s not fun. But I take tremendous pride in thinking we had some hiccups, some speed bumps, but that locker room is incredible. The character in that locker room speaks volumes for the type of people there.

“Not just basketball. We start with people first. You have to grow with great people. Sure, they have to be great basketball players. Now there’s a maturity. There’s experience there. There’s confidence.’’

With athletic director Josh Whitman in the back of the room, it was time to exhale for just a second and realize the Illini were headed to the NCAA Tournament for the first time since 2013 and looking like a team that will roll into postseason play and ready to take off.

“We’re still really young, and yet there’s a tremendous amount of experience present,’’ Underwood said. “ It’s something I’m really proud of. Building is not easy. We’re not where it needs to be, but we’re climbing the mountain.’’

(In the meantime, Northwestern slid down to the bottom of the Big Ten, and the job security for coach Chris Collins appears to be on less than solid ground.)

The Illini still rely on the blue-collar work ethic of defense and rebounding, but the skill level is improving. The game-winners by Ayo Dosunmu are A Thing, much more reliable than anything since Dee Brown left town. But the Illini also have some scoring depth. On days when Trent Frazier goes 3 of 14 and Feliz is 1 of 8, sophomore Alan Griffin comes off the bench to shoot 9 of 11 and finish with a career-high 25 points to provide the Illini an answer.

Griffin was the fifth Illini to score 20 points or more in a game this season, allowing the Illini “to be a team that’s not a one- or two-person team. We have multiple guys. He’s a guy who comes off the bench. Having that piece is pretty nice.’’

But that defense and rebounding is still the foundation for Illinois, and those variables play well in postseason when the tempo often slows down and each possession means so much more.

Illinois changed its defensive approach, pulling back the pressure to play a more traditional approach, and the Illini no longer play themselves out of position. When the offense cools off, the Illini no longer worry about the ball not going in the basket, Underwood said.

“One thing we can control is what we do on the defensive side and rebounding side,’’ Underwood said. “We made huge strides there. That’s how you win. You win with defense. If you’re not scoring, you better make sure the other team isn’t scoring either.’’

The Illini continue to grow, a program that’s taking the training wheels off and preparing to hang with the big boys again in March Madness. It’s been seven years, and Underwood feels Illini have that kind of solid foundation to make this longer than a one-hit wonder.

The Illini have grown enough to get back into the game. Illini fans have taken notice, and, just for a moment, Underwood allowed himself to exhale and appreciate the climb and his role in rebuilding Illini Nation.

“It makes you smile when you’re a part of it,’’ he said. “That unbelievable feeling to know how proud our fans are of us, walking around with their heads held high. I’m damn proud to be a part of it.’’

The foundation is built, Underwood said. It’s time to start working from the ground up.