The first big domino to fall in the NBA offseason wasn’t a trade, a free agent signing or a draft selection.

No, it was what happened to Kevin Durant on Monday night.

The Golden State Warriors forward exited Game 5 of the NBA Finals with what his team reportedly believes is a torn Achilles. Golden State eventually earned a 106-105 win over the Toronto Raptors to force a Game 6, but that’s not what everyone is talking about.

If Durant’s right Achilles truly is torn, it could have a major impact on the directions of multiple franchises and potentially alter the course of NBA history. It’s that big of a deal, like it or not.

But for now, let’s focus on the Boston Celtics.

It’s been widely reported that Durant and Kyrie Irving — both of whom can opt out of their current deals and become free agents in July — are/were strongly considering joining forces and signing with a New York team, be it the Knicks or Brooklyn Nets. Recently, there’s been more talk of Irving zeroing in on the Nets, but the Knicks rumors remain prevalent nonetheless.

Durant has a $31.5 million player option he could exercise to remain with the Warriors, should his Achilles injury lead to depressed interest on the open market. If that happens, many believe the door opens for Irving to return to Boston, either on a long-term deal or something far shorter, allowing him to reassess his situation next summer.

Furthermore, with Irving back in the fold, Danny Ainge seemingly would be more willing to part with major assets to acquire Anthony Davis in a blockbuster trade. Recent reports indicate Ainge’s interest in Davis is steadfast and unaffected by Irving, but re-signing the point guard surely would embolden the Celtics in their pursuit of the New Orleans Pelicans superstar.

(That is, if the Celtics are even willing to satisfy New Orleans’ reported lofty demands.)

Check out this tweet from NBA insider Steve Kyler:

And then there’s this excerpt from a column published by NBC Sports Boston’s Chris Forsberg on Tuesday:

“It’s always felt like Durant’s decision would have a domino effect among star players this summer. Maybe it still will, but there’s a lot more for players to ponder.

“All of which adds a bit more intrigue to what happens with Anthony Davis in the ramp-up to next week’s NBA Draft. If Durant’s injury gives Irving even more reason to consider staying in Boston, then the Celtics going all-in to acquire Davis could ensure Irving stays here.”

Of course, there’s the possibility that Irving is intent on leaving Boston regardless of what Durant does, a notion the Celtics reportedly already believe. Moreover, there are rumblings Boston has shifted its focus toward other trades and/or free agent signings in an effort to strengthen a core of young stars Jaylen Brown and Jayson Tatum.

One of the Celtics’ reported targets is Houston Rockets star big man Clint Capela, although such a trade seems unlikely considering Boston’s salary cup situation.

How this dizzying game of NBA musical chairs ends is anyone’s guess. But there’s a real possibility that, in a year’s time, Celtics fans will look at Durant’s injury as one of the most significant turning points in franchise history.

Thumbnail photo via Winslow Townson/USA TODAY Sports Images