Are you sure about those .9 seconds?

The clock went from 2.1 seconds to a full three seconds after Jimmy Butler was fouled shooting a 3-pointer at the end of Game 6 of the Eastern Conference Finals on Saturday night.

Butler made all three free throws to put the Heat up 103-102, but those extra ticks on the clock made all the difference as Derrick White’s putback came with .1 seconds left.

The league explained the extra time was added to the clock after Celtics coach Joe Mazzulla unsuccessfully challenged the foul call against Al Horford.

“Replay review of the foul called on Horford pursuant to a coach’s challenge was deemed unsuccessful,” the NBA’s Last Two-Minute Report stated after the Celtics’ 104-103 victory.

“Horford made contact with Butler during his shooting motion and a foul was warranted. During the review, the Replay Center Official also determined that i) the foul occurred at 3.0 seconds and adjusted the clock accordingly; and ii) Butler’s shot attempt was taken from behind the three-point line, and therefore three free throws were awarded.”

The decision ended up saving the Celtics season.

It’s safe to say Heat fans are not exactly buying the NBA’s explanation.

The report also revealed that there were two calls that should have gone against Miami: A missed lane violation against Caleb Martin on a Jaylen Brown free throw with 1:01 left and a Jayson Tatum drive that should have resulted in a Gabe Vincent foul with 33 seconds remaining.

Boston has now won three straight games after falling in a 3-0 hole with Game 7 scheduled for Monday night.

“We’ve got another chance, another opportunity,” said Tatum, who had 31 points, 11 rebounds and five assists in Game 6. “It’s far from over. Still an uphill battle. But it always feels good to give yourself another chance, another opportunity.”

The winner will face the Nuggets in the NBA Finals after Denver swept the Lakers in the Western Conference Finals.