They are the five letters no No. 1 NCAA Tournament seed ever wants to see: Upset.

Thursday marks the five-year anniversary of University of Maryland-Baltimore County — the tiny school few fans had ever heard of, let alone picked in their bracket — pulling off the biggest upset in college basketball history by beating the tournament’s top seed in Virginia.

UMBC’s lasting legacy became this: If you don’t watch out, No. 1 can mean one-and-done.

While there were some close calls before 2018, No. 1 seeds had gone 135-0 before UMBC routed Virginia 75-54 at Charlotte’s Spectrum Center. Now they are 1-147. Like the men, the women’s side of March Madness has seen only one 16 knock off a 1: Harvard over Stanford in 1998.

On Thursday, three more No. 1 seeds — Alabama, Kansas and Houston — take the court looking to avoid what the Cavaliers endured five years ago, while their respective opponents Texas A&M-Corpus Christi, Howard and Northern Kentucky look to capture that “One Shining Moment” and etch their name in history alongside the Retrievers.

Ryan Odom, the Retrievers coach that season, said after the game “these are the moments that you dream of.” while his players celebrated in a cramped locker room after shocking the world. Diminutive 5-foot-8, 140-pound guard KJ, Maura and his teammates joked about there being “no more perfect brackets” and possibly becoming the focal point of a future ESPN “30 for 30” episode.

Some players struggled to process the enormity of the moment, hugging each other long and hard.

“It felt like my soul left my body, man,” UMBC guard Jourdan Grant said that day.

Odom, now the head coach at Utah State, a No. 10 seed in this year’s tourney, said Wednesday it was “a memory that will last a lifetime.”

“Will a 16 ever beat a 1 again? I have no idea,” Odom said. “It takes a special group. It takes a lot of luck in order to have a chance to win any game in the NCAA Tournament.”

Former UMBC guard Joe Sherburne said it remains the single greatest day of his life.

“You can measure my life by this: before that day, and after that day,” Sherburne said Wednesday. When friends introduce him to people, the first thing they say is “Joe played for UMBC.”

Sherburne, who works as a financial adviser, remembers the day well.

As UMBC’s lead over Virginia grew to double digits in the second half he sensed something special, something miraculous was happening. He struggled to concentrate on the next play call while sitting on the bench during TV timeouts: “I felt like I was in shock.”

Could this really be happening? Could a 20 1/2-point underdog really beat the No. 1 team in the nation in the NCAA Tournament?

But it happened — and everyone suddenly wanted to know their story.

Sherburne stayed at the arena until 1 a.m. doing interviews before returning to the team hotel where he was greeted by overwhelmed fans, friends and family members. He and his teammates watched “Sports Center” on repeat and ate pizza, basking in the moment.

“We were all still running on adrenaline,” Sherburne said. “I couldn’t eat or drink. I can usually eat a whole Domino’s pizza by myself, but I couldn’t that night. I might have had two or three slices.”

Sherburne still wishes the celebration had gone on for days longer, but UMBC lost a close second round loss to Kansas State two days later.

Still, there will always be the satisfaction of accomplishing something that had never been done before. Sherburne is hoping it stays that way for awhile.

After the final 16 seed lost in last year’s NCAA Tournament, he toasted UMBC’s legacy with a shot of whiskey.

Two years ago, he attended Game 6 the 2016 NBA Finals where he watched former Virginia big man Mamadi Diakite win a championship ring. Diakite was one of six Virginia players from that team to play in the NBA; UMBC had none.

“I’m sitting in the arena that night, in the second row from the top, thinking to myself, ’You know, just a couple of years ago I was making this guy and his teammates cry,’” Sherburne said.

UMBC players haven’t had an in-person reunion, but Sherburne said players remain in touch on group texts.

Last week, Odom opened one of those texts to find players and assistant coaches reminiscing about star guard Jairus Lyles’ buzzer-beater to beat Vermont in the 2018 America East Conference Tournament championship game — a dramatic win that earned the Retrievers an automatic bid to the Big Dance.

Odom’s eyes swelled up with tears as he scrolled through the comments and pictures.

“Each team that we’re fortunate enough to coach has one life to live,” Odom said. “That particular team lived a great life. The joy that that team experienced was unlike any other. Certainly the memories that we’ll all take from that particular season will last a lifetime. This is what all coaches and players want: they want to be a part of March Madness and the upset.”.