DALLAS — The smallest player on the court pulled off perhaps the biggest upset in women’s college basketball history. Morgan William, all 5-5 of her, nailed a pull-up jumper at the overtime buzzer to give Mississippi State an unfathomable 66-64 victory over No. 1 Connecticut last night in the semifinals of the NCAA women’s Final Four at American Airlines Center.

The guard nicknamed “Itty-Bitty” had a potential winning shot blocked in the final seconds of regulation but came up huge in overtime to send the Bulldogs (34-4) into Sunday’s championship game against South Carolina.

“It’s just an incredible experience right now,” William said on the court after the game. “I live for moments like this. UConn, I mean, they’re an incredible team. For me to make that shot against them, it’s unbelievable. I’m still in shock right now.”

“I saw I got enough separation to get it off so I wouldn’t get it blocked, because last possession I got it blocked with the layup, so I figured I could pull up and take a jumper this time.”

Connecticut (36-1) entered the game riding a record 111-game winning streak and four consecutive national titles, and had crushed Mississippi State by 60 points in the 2016 NCAA Tournament.

Trailing by four in the final minutes after a tough layin by Bulldogs guard Victoria Vivians, UConn pushed back. After Katie Lou Samuelson buried a three-pointer to close the gap to one, Saniya Chong hit two free throws to give the Huskies a 57-56 lead.

Then Gabby Williams, who led UConn with 21 points, stole the ball at midcourt and finished the play with a layup and a three-point edge.

But Vivians made a free throw, and she hit a long three that went down to put MSU on top again with 1:14 to go. Napheesa Collier’s free throw with 27 seconds left tied it and gave the Bulldogs a chance to get a final shot. But William’s drive was blocked by Williams to send it to overtime.

Vivians, the Bulldogs’ top scorer with 19 points, fouled out in OT. But they edged ahead again at 64-62 when 6-7 center Teaira McCowan dropped in a layup with 1:12 left.

But UConn got a break when Samuelson took an elbow to the throat from MSU’s Dominique Dillingham — a flagrant foul that gave UConn two free throws and the ball. Samuelson made both shots to tie it again with 26.6 seconds left, but Saniya Chong lost the ball while driving.