Any flickering frustrations from the regular season faded way Friday night as Kentucky beat arch-rival Louisville 74-69 in the NCAA Tournament Sweet 16.

All the “clutter,” as Coach John Calipari called it, about six McDonald’s All-Americans, a 40-0 record and what The Wall Street Journal mockingly called the construction of a Death Star.

The March 1 loss at South Carolina seemed so long ago, from a different season, as Kentucky followed up its invigorating victory over No. 1 seed Wichita State last weekend with a pulsating comeback against Louisville.

Kentucky, which will play Michigan Sunday in the Midwest Region finals, trailed 66-59 with barely four minutes left.

Alex Poythress hadn’t scored. Then he scored six points down the stretch. His dunk off an Andrew Harrison whip pass got the comeback started. His put-back/three-point play tied it with 2:13 left. His free throw with 1:26 left put UK ahead 67-66, the Cats first lead since 2-0.

After Russ Smith hit a pull-up jumper in the lane to put Louisville ahead 68-67 with 1:09 left. Aaron Harrison hit the decisive shot. Taking a pass from Julius Randle, whose move drew defenders, Harrison swished a three-pointer from the left corner with 39.1 seconds left.

On the 22nd anniversary of Christian Laettner’s famous buzzer-beater against Kentucky, the Midwest Region doubled down on drama. Michigan beat Tennessee 73-71 in the earlier semifinal when the Vols missed a half-court heave.

Fittingly, the free throw line separated the winners from the losers. U of L, which made only 13 of 23 free throws, had a chance to tie it with 14.2 seconds left. But Wayne Blackshear, a 75-percent free thrower, made only one of two.

UK, which made 22 of 27 from the line, clinced it when Randle and Aaron Harrison each made two of two in the final 13 seconds.

Randle, Aaron Harrison and Dakari Johnson led UK (27-10) with 15 points each. Johnson came up big in relief of Willie Cauley-Stein, who left the game in the first half with an injured ankle.

Louisville, 31-6, got 23 points from Smith and 190 from Luke Hancock.

Kentucky trailed 34-31 at halftime, and had to be happy.

The Cats made only a third of their shots in the first half (10 of 30), fell behind by as much as 13 points early and saw Willie Cauley-Stein limp off the court with13:05 left.

Yet, Kentucky kept competing, drawing as close as a point of Louisville down the stretch.

U of L helped Kentucky’s chances by making only six of 15 free throws in the first half.

Twice inside the first eight minutes Kentucky called timeout to try to blunt Louisville’s early momentum. With UK launching six three-pointers in its first 10 shots (the good perimeter shooting against Wichita State last weekend did not endure), Louisville led 18-5 early.

Smith had six of his 15 first-half points in that early breakout. Wayne Blackshear, who entered the game when Luke Hancock picked up two early fouls, capped the run by beating his man on a cut for a layup.

Cauley-Stein limped off the court with 13:05 left in the first half.

Randle’s first points -- a layup off a lob with 11:33 left -- began Kentucky’s long slow climb back into the game. UK’s first three-pointer -- by Aaron Harrison wtih9:23 left -- after six misses from beyond the arc gave UK renewed hope.