Mohegan — In a season filled with exasperating “what the hell” moments for the Connecticut Sun, Thursday night was their most “WTH?”

Connecticut led the defending champion Phoenix Mercury for the majority of the game, injuries and losing streaks be damned.

And then Phoenix reserve Leilani Mitchell sank the Sun with an off-balance 3-pointer and handed them their sixth straight loss 81-80, before a gobsmacked 5,171 at Mohegan Sun Arena.

All-star Alex Bentley (ankle), starter Alyssa Thomas (shoulder) and reserve Elizabeth Williams (knee) didn’t play again due to injuries for Connecticut (12-16).

Those three injuries came months after Connecticut lost five players to injury before the regular season, including two starters.

The Sun trailed 29-17 a minute into the second quarter of Thursday’s game.

Connecticut fought back and took the lead with 4 minutes, 12 seconds left in that quarter. It led by as much as 57-46 with 5 minutes, 55 seconds left in the third quarter. It held that advantage until the final 24 seconds.

When it rains, it pours anvils.

“Somebody around here has some (bad) karma that I hope they are done with,” Connecticut’s Kelsey Bone said. “It’s tough.

“There’s only maybe only two games that I can recall that we’ve actually been beat, just beat, where we’ve gone out and laid and egg. And every (loss), it’s 10 points or less. To just be there (so close to winning), and to just be there, and to just be there (and lose), it is (tough).”

Connecticut dropped four games behind the fourth-place Washington Mystics (15-11) in the Eastern Conference standings with six games remaining. The Sun mathematically trail Washington by five as the latter won the head-to-head series. The top four teams in each conference make the playoffs.

The Sun began the season 7-1. They’re now just a half game ahead of the last-place Atlanta Dream.

DeWanna Bonner had 26 points and six rebounds for the Mercury (17-11) and Brittney Griner had 14 points, 13 rebounds and three blocks.

Mitchell scored 16, including four 3-pointers.

Jasmine Thomas scored a career-high 21 with four assists for the Sun (12-16) and Camille Little had 16 points, five assists and four rebounds. Bone added 13 points and seven rebounds.

The shot clock was about to run out on Phoenix when Bonner made a 3-pointer to give her team a 78-77 lead with 24.2 seconds remaining in the game.

Thomas made an 18-foot jumper with 9.6 seconds left to put Connecticut back ahead. Bonner was called for an offensive foul seconds later.

Thomas made the second of two free throws with 4.8 seconds left.

Mitchell shot her game-winner over both Thomas and Little.

“It was a bit of a broken play,” Mitchell said. “The play was supposed to get into DB (Bonner) and as you saw she got tripped up. Noelle (Quinn) made a good play, attacked, kicked it out to me and I just tried to put up a good shot before the clock expired.”

Sun head coach Anne Donovan said: “I feel like we just left everything out there that we could’ve possibly left out there and I think we deserved that win, but that’s the unfortunate thing about sports. You don’t get what you deserve a lot of times or what you worked for but this was one of those games where I feel like we did a lot of things right.”

n.griffen@theday.com

Twitter: @MetalNED