We may not know until Tuesday night, but the LSU Lady Tigers may have finally come face to face with an addition-by-subtraction equation they won’t be able to solve.

Taking on Penn State in an NCAA tournament second-round game Tuesday will be difficult enough. The Lady Lions, back-to-back Big Ten champions, turned in what looked like B-minus work and still easily worked over NCAA first-timer Cal Poly 85-55 in Sunday’s first game.

Now the Lady Tigers may face an even tougher degree of difficulty pending the diagnosis of junior guard Jeanne Kenney.

The Rocky Balboa of this Lady Tigers team and perhaps the toughest LSU athlete — man or woman — this reporter has covered in the past 21 years, Kenney crumpled to the Pete Maravich Assembly Center floor with 44.1 seconds left after a head-to-head collision near midcourt with teammate Adrienne Webb.

There was no word on Kenney’s condition, but anytime an athlete has to be carried to the locker room, especially one seemingly made of iron, it can’t be good.

And LSU simply can’t afford to lose another key player. Not now. Not against a team as good as Penn State.

LSU has won eight of its past nine games, playing its best basketball, but its roster has started to resemble the vanishing cast of “Ten Little Indians.”

Coco Baker got the boot after numerous off-the-court transgressions. That cut the roster to nine. Sheila Boykin came down with Guillain-Barré syndrome and was made into a permanent fixture on the LSU bench. That left the Lady Tigers with eight.

OK, the Lady Tigers have adjusted to that. A lot of teams only play with a seven- or eight-person rotation. Green Bay did. But Kenney’s play in the starting lineup or off the bench is often the booster shot of adrenaline LSU’s offense — or defense — needs at critical times.

Can LSU beat Penn State without her? Sure, theoretically, anything is possible.

But each player on the roster who gets crossed off the list like one of Agatha Christie’s whodunit suspects increases the pressure on the remaining players. Eventually, the Lady Tigers could shrink to a point of critical mass and not be able to endure any more.

For her part, LSU coach Nikki Caldwell’s postgame body language didn’t scream “Kenney can’t play” like an ambulance siren. Her mood, as one might expect after such a hard-earned victory, seemed buoyant.

“Bless her heart,” Caldwell said of Kenney. “She has been on that floor more than the free-throw line. You think about how many times she has taken charges.

“We hope she bounces back.”

The Lady Tigers had better convert that hope into a prayer for Kenney’s swift recovery as LSU fights for its first Sweet 16 berth since its last Final Four foray in 2008.

Because they don’t stand a prayer without her.