Just minutes into their opening game of the season, the Boston Celtics suffered a huge blow after Gordon Hayward sustained a gruesome injury that would rule him out for the year and in the eyes of many, end the team's chances of success.
Witnessing their teammate's pain clearly had an impact on the Celtics players the night after as they were beaten at home by the Milwaukee Bucks.
Questions were immediately raised about how they could recover from this major setback. 12 games later, they have answered every question emphatically.
Since that defeat to the Bucks, Boston has gone on a 12-game winning streak and are the best team in the Eastern Conference.
Kyrie Irving has been playing like the superstar he is, Al Horford has been tremendous and youngsters Jaylen Brown and Jayson Tatum have played with a maturity beyond their years.
But their brilliant start to the campaign wouldn't be possible without the brains behind the operation, head coach Brad Stevens.
Of the many moves general manager Danny Ainge has made during his time in the front office, hiring Stevens has to be up there with the best.
Since being hired in 2013, he has worked miracles with the Celtics and has overcome every obstacle and challenge thrown at him to continue to make them competitive.
After building a roster that reached the conference finals last season, it was almost completely dismantled and he was tasked with starting again with a largely new group of players.
From the team that was beaten in four games by the Cavs, only four players were retained; Horford, Brown, Marcus Smart and Terry Rozier.
The likes of Isaiah Thomas, Avery Bradley, Jae Crowder and Kelly Olynyk all left the organisation either via trades or free agency.
Stevens was presented with a younger squad and has worked his magic, even after losing Hayward.
The true measure of his coaching ability has been in full effect over the last two games after Irving suffered a facial fracture just a minute into their home encounter with the Charlotte Hornets.
They were already without Horford who was out with a concussion and they had to play the next 47 minutes without any of their big three in the lineup.
Most NBA teams would struggle to cope without their best player, let alone three. Think of the Cavaliers without LeBron James or the Houston Rockets without James Harden. Their chances of winning would decrease dramatically.
Stevens doesn't allow that to happen in Boston. Down by as many as 18 points to the Hornets, he rallied his troops after they predictably struggled offensively.
They scored just 11 points in the first quarter after Kyrie went down and shot 5-for-19 from the field. But their coach wasn't going to allow them to use their absentees as an excuse.
The C's incredibly turned the game around in the second half and fought their way to an unlikely victory.
Young guard Terry Rozier explained after the game how Stevens inspired them by telling them they were going to win and saying "this place is gonna go crazy." That's exactly what happened.
As impressive as that was, it was against a Charlotte team with a losing record which maybe took some of the gloss off it. But that can't be said about their 12th win on the bounce against the Toronto Raptors on Sunday.
The Raps came into the contest with a 7-4 record but became the latest victims to the red-hot Celtics, even though Irving was missing.
So what's the secret to their success?
The system that Stevens deploys is a winning formula and he's able to adapt to the players at his disposal by using them in the right way and giving them a clear structure to follow on the floor.
“Brad is a mastermind when it comes to coaching,″ said Marcus Morris, per the Patriot Legder. “He puts guys in the right spots and strong areas to where they can succeed well at.
“He knows matchups and plugs guys in. He knows what they do best offensively and defensively.″
Morris was acquired from the Detroit Pistons in the trade that sent Bradley in the opposite direction but has only played in five games after just recently recovering from an injury.
Calling his new coach a "mastermind" after working with him for a short amount of time is a testament to his skills.
The 41-year-old is one of the youngest coaches in the league but he is already among the best. Irving caused controversy recently when he said Stevens is exactly the kind of coach he was "craving".
“Brad fits perfectly in terms of that because he has an intellectual mind and is an intellectual human being,” Irving said. “It was something I was unbelievably craving in terms of what I wanted for my career.”
The four-time All-Star may be the team's best player but regardless of who's on the court for Boston, it's clear that the man orchestrating things from the sidelines is their biggest asset.
With him at the helm, the franchise is destined for greatness once again.