AL HORFORD SNAGGED the rebound near the 3-point line as the clock ticked down, the score tied at 54. It was March 23, 2007. On the other end, the 6-foot-9 forward backed down a defender who was four inches shorter than him and 20 pounds lighter. As he drew closer to the basket, the whistle blew, and Horford softly laid the ball in the basket. With 2:34 left, Horford nailed the free throw, giving his Florida Gators a lead they wouldn't relinquish in the Sweet 16 of the NCAA tournament. On the sideline, Brad Stevens, then an assistant coach with the Butler Bulldogs, couldn't believe the call. He still can't now, 17 years later. "It was a charge," Stevens told ESPN. "It could've gone either way," Horford told ESPN. The Bulldogs, an underdog mid-major, were facing a top-seeded Gators squad seeking to repeat as national champions. The Gators boasted five future NBA players, including Joakim Noah, Corey Brewer and Horford, while the Bulldogs possessed zero top-100 recruits. Entering the game, Stevens considered Horford the Gators' best player, a handful in the lane with a soft-shooting touch from midrange. And Horford viewed the Bulldogs as one of the best-coached teams his Gators had faced. Florida prevailed behind Horford's effort -- 16 points, 7 rebounds, 4 blocks and 2 assists -- and cruised to a second straight title. At the time, the contest seemed little more than a fierce game in the furnace of March Madness, but, as years passed, and as both Horford and Stevens reached the NBA, it would come to represent something more: the beginning of an unlikely bond. For years, Stevens and Horford admired each other from afar as their professional paths wound through the league, sharing deep respect for the other and their ideals about the game. They separately imagined a partnership. Now in Boston, they each stand two wins away from their first NBA championship. A title for the 38-year-old Horford -- the oldest player remaining in the playoffs -- would punctuate a 17-year NBA résumé and honor his impactful postseason run, during which the Celtics hold a +13.6 net efficiency with Horford on the floor, the best among 100-plus players to average 20 minutes per game this postseason. It would also end a painful drought; Horford has played the second-most playoff games of all time (183) without a title, trailing only Karl Malone (193). A championship would also serve as a crowning achievement for Stevens, the Celtics' president of basketball operations who recently earned NBA Executive of the Year honors after constructing a roster that has brought Boston to the brink of its 18th championship. But, perhaps above all else, a title would represent a coda for their own journey that began all those years ago. "I don't think there's any question that everybody in this building wants the very best for Al," Stevens said. "He has been such a huge part of all of our journeys." None, perhaps, bigger than Stevens' own.

LESS THAN TWO weeks after that first encounter in 2007, Stevens became Butler's head coach, and led the Bulldogs to national championship appearances in 2010 and 2011. Horford, meanwhile, was the third pick in the 2007 NBA draft and joined the Atlanta Hawks, establishing himself early, playing in a first-round playoff series against the eventual-champion Celtics, led by Kevin Garnett, Paul Pierce and Ray Allen. Horford averaged 12.6 points and 10.4 rebounds. The series went seven games. Stevens watched from afar. "His character and his reputation as a winner preceded him," Stevens said. "Everyone knows who those guys are. You can't fake it very long. He's always had that." As his own NBA career began to unfold, Horford watched Stevens' teams at Butler, and later, when Stevens departed Butler to become the Celtics' head coach in 2013, the two faced each other regularly. "Very tough-minded teams," Horford said. "Hard-playing, execution on offense was flawless, very difficult to prepare against them." "[Stevens] found a way to get the most out of each player that he had. That's the thing that impressed me the most about him." (That, Horford adds, and Stevens' playcalling.) But, in many ways, they saw in each other some of themselves -- the way they felt about the concept of team: being part of a collective that, when everyone pulled together, could achieve more. "We're very much on the same page, and we both very much care," Stevens said. "That is clear as day with him. He enjoys the camaraderie part of it. He enjoys everybody playing for one reason. It's really inspiring to be around him because of that -- that concept of we're in this together, we share results and we're gonna give it all for each other. Though it may sound cliche or may sound cheesy, that's what it's all about. That's why he's so special." And, of course, Stevens imagined one day coaching Horford. "There's no question when you play against certain guys and you watch the impact they have on the court with their play, but more so how their teammates react, respond and play around them, you just highlight 'em and you hope that someday they could play for the Boston Celtics," Stevens said. "And he was certainly at the top of that list for me." When Stevens was hired as the coach of the Celtics in July 2013, the team was entering a painful rebuild after trading Garnett and Pierce to the Brooklyn Nets. Stevens' early teams mirrored some of his at Butler -- overmatched underdogs -- but proved a tough out, even reaching the first round of the playoffs in his second and third years. To take the next leap, though, the Celtics required a star, and, in the summer of 2016, they were in position to land one. That summer, Boston met with former NBA MVP Kevin Durant, and the Celtics pitched him in the Hamptons, with New England Patriots star Tom Brady even joining their cause. But along with Durant, there was another target the Celtics -- and Stevens -- were chasing: Horford. The four-time All-Star had led the Hawks to 60 wins in 2014-15 and an Eastern Conference finals appearance. But Horford was also a more complete player than the one Stevens had seen years earlier. That change came in Atlanta, Horford says now, when former Hawks executive Rick Sund pulled Horford aside and told him that adding the 3-point shot to his arsenal would extend his career. "I was just blown away with all the layers of it," Horford said. On July 2, Horford tweeted his decision: "Celtic Pride!!!!" with 18 four-leaf clover emojis -- the number signifying the championships he hoped to bring a team that already possessed 17. Horford agreed to a four-year, $113 million deal, becoming the biggest free agent signing in Celtics history. After years of distant admiration, Horford and Stevens had united, and Stevens would soon learn how much Horford would impact every corner of the franchise, including on the team's rising superstar duo.

GROWING UP, HORFORD watched his 7-foot-1 father, Tito, finish out short stints in the late 1980s and early 1990s with the Milwaukee Bucks and the Washington Bullets. He watched him play professionally in Spain, France, Italy and in semipro leagues in his native Dominican Republic. And when he stood by his father's side, one thing Horford noticed was his father's discipline in how he took care of his own body. Those lessons have shaped Horford ever since. He calls his routine now "boring and simple": aiming for seven to nine hours of sleep per night -- plus a nap during the day, eating good proteins, stretching before practice, lifting weights, and monitoring when to have more rigorous workouts or to scale down. Horford brought those habits to Boston at a time when the team possessed young cornerstones. Horford's first season in Boston was also then-rookie Jaylen Brown's first. Jayson Tatum arrived one year later. Horford's approach with both of them was simple, he says now: Don't look down on them because they're young or inexperienced. Instead, help them in any way possible. Be generous. Share knowledge. That approach, Stevens said, was monumental. "He really cares about Jayson and Jaylen," Stevens said. "When I talk about his patience, he's known how special they were the whole time. He's patient through each step of the process to help them grow." Earlier this season, Tatum talked about how Horford had mentored him during his rookie season. Quickly, he said, he gained deep respect for Horford's professionalism. "He was never late, always on time, always getting his work in, in the gym, always taking care of his body," Tatum said then. "I learned a lot from him from a routine standpoint, and as I've gotten older, our relationship has grown. It's based off respect: the respect that I have for him and likewise. And we know we need each other. And even when I was 19 and now, he still asks me questions, asks me, 'How am I feeling? ' and 'How's my body?' That's who I sit next to on the plane. Al's my favorite teammate I ever had." During the Eastern Conference finals between the Celtics and Indiana Pacers, Tito was riding to a game in Indianapolis alongside other parents, including Tatum's mother. "My son has learned so much from Al," she told Tito, who beamed with pride. With Horford, the Celtics took a step forward, reaching the Eastern Conference finals in his first two seasons in Boston, the furthest the team had advanced since Garnett, Pierce and Allen. Horford earned his fifth All-Star appearance in his second season with the team. The next season, the Celtics fell to the 60-win Bucks in the second round and Horford departed in free agency, signing a four-year, $109 million contract with Philadelphia. The move didn't pan out. Horford was demoted to backup center in Philadelphia and was traded after one season to Oklahoma CIty, where he played sparingly and agreed to sit out the final 28 games of the 2020-21 season. By the summer of 2021, Horford was 35 and questions loomed about his future. That same summer, Danny Ainge retired as the Celtics' president of basketball operations, and Stevens was promoted to replace him. Stevens now possessed the authority to shape the team's roster, and he didn't wait long to make his first move.

TWO WEEKS AFTER Stevens' promotion, Horford was driving through Atlanta with his family when he received a phone call. It was his agent. Something might be happening, he said. Horford wasn't sure what that meant. He and his wife had been hoping that if they could play anywhere again, it would be back in Boston. Soon after his agent's message, Horford's phone rang again. This time it was Stevens. Horford pulled to the side of the road. "We're going to bring you back," Stevens told him. Horford screamed with joy in the car, as did his wife and kids. The news soon broke: The Celtics were trading guard Kemba Walker and a first-round pick to the Thunder for Horford. (The Thunder also sent center Moses Brown to Boston, and the two teams swapped future second-round picks.) Horford called his parents, telling them how happy he was and that he had unfinished business in Boston: winning a championship. That season, the Celtics reached their first NBA Finals in more than a decade before falling to the Golden State Warriors in six games. The next season, the Celtics reached the conference finals under first-year coach Joe Mazzulla, losing in a seven-game series to the Miami Heat. The Celtics were now on the doorstep of the title they all craved so desperately. But they needed more to reach that final goal. In June 2023, Stevens traded for center Kristaps Porzingis, who averaged a career-high 23.2 points, 8.4 rebounds, 2.7 assists and 1.5 blocks with Washington the season prior. Then, in October 2023, the Celtics traded for guard Jrue Holiday, one of the NBA's best two-way players.