Could Jayson Tatum's injury end this iteration of the Celtics?

Jayson Tatum's pain was palpable. 

After lunging toward the ball with 2:58 left in Game 4 of the Boston Celtics' second-round playoff series against the New York Knicks on Monday, he collapsed onto the court. 

While lying on the hardwood at Madison Square Garden, he writhed 360-degrees. He grabbed at his right leg. He curled his head into his neck. 

After he was carried off the court in a wheelchair, he covered his face with both hands, overwhelmed by a gut-wrenching combination of pain and mental anguish. 

An MRI on Tuesday confirmed everyone's fear: Tatum suffered a torn Achilles tendon. 

The ramifications of such an injury are not only devastating for the 27-year-old superstar, but for the Celtics, who won a championship last season and whose hopes of remaining contenders now and in the near future are now upended. 

It can take a year to return from an Achilles tear. And even after a player comes back, he's often never the same. 

That's an incredible blow for the Celtics, who had stormed into the center of the basketball universe the last four years with two Finals appearances and an 8-2 record against Eastern conference teams in the postseason. Last year, they sailed through the playoffs with a 16-3 record en route to winning their first title in 16 years.

This was the Celtics' time. 

Tatum and Jaylen Brown had finally figured out how to be complementary stars by putting aside their egos. They shrugged off Dallas Mavericks coach Jason Kidd calling Brown the best player on the team during the 2024 Finals, something that was widely considered to be a tactic intended to divide them. Tatum celebrated Brown winning Finals MVP. They had learned to root for each other instead of themselves. Meanwhile, Jrue Holiday, Derrick White and Kristaps Porzingis had developed into stars in their roles. 

Now, after watching Tatum crumple to the ground Monday, the Celtics' entire calculus has changed. In all likelihood, this is the end of this iteration of the franchise. 

The Celtics now face a 3-1 series hole against the New York Knicks and an even bigger existential dilemma: What's next for this team whose window for greatness has significantly shortened?

Will the Celtics deal Holiday and Porzingis? Does Tatum's injury open the door for them to move Brown in what's shaping up to be a very interesting trade market, with both Giannis Antetokounmpo and Kevin Durant potentially up for grabs?

Tatum and Brown have played together for eight seasons. Now, everything has changed for a team that was built on continuity. 

And now everything has also changed for a player built on durability (Tatum, who had helped lead the Celtics to the postseason in each of his eight years with the team, hadn't missed a postseason game in his career until this run.)

For Tatum, his reaction as he was wheeled off the court reflected a pain that was much deeper than the injury he suffered. 

This could be the end of everything he had poured himself into since he was drafted by the team as the third overall pick in 2017. 

Tatum had 42 points, eight rebounds, four assists, four steals and two blocks in Game 4 before his tendon gave out on him, doing everything possible on both ends of the court to prevent the Celtics from falling into an ominous 3-1 deficit. 

But in the end, it wasn't enough. And when he went down, the Celtics not only lost their superstar, but the vision they had for their future.

It's highly unlikely that the Celtics will foot an exorbitantly high luxury tax bill for a team that Tatum – whose five-year, $313 million extension last summer became the largest NBA contract ever – won't even suit up for next season. 

And even before Tatum's injury, the Celtics' weaknesses had been exposed. The Cleveland Cavaliers surpassed the Celtics as the No. 1 seed in the Eastern Conference. Boston had a shaky December and January, losing nearly as many games as they won. And now, after dropping their first two home games against the Knicks and then losing essentially a must-win Game 4, the Celtics are on the brink of an unexpectedly early playoff exit. 

For a team that was popping bottles of champagne last June and now navigates an uncertain future under a new owner, change is coming. 

And for Tatum, in the blink of an eye, everything devolved into a giant unknown. 

Melissa Rohlin is an NBA writer for FOX Sports. She previously covered the league for Sports Illustrated, the Los Angeles Times, the Bay Area News Group and the San Antonio Express-News. Follow her on Twitter @melissarohlin.