ATLANTA – If the first half of Tuesday night’s Champions Classic game showed how good Duke can be against an elite team, the second half put Duke’s flaws on display for the first time.

The result — a 77-72 loss to Kentucky at State Farm Arena — leaves a taste of both bitterness and optimism.

The former is obvious, as the sixth-ranked Blue Devils lost for the first time this season. Boilerplate bitterness comes from holding a nine-point halftime lead and having it erode in the second half, as Duke (2-1) was 1-for-11 on 3s in the second half.

And the lasting images of freshman Cooper Flagg turning the ball over twice in the last 20 seconds — first when the score was tied, and then when Duke was down by two — will be hard to shake. It doesn’t undo the 26-point, 12-rebound game the 17-year-old had; it just introduces skepticism that will have to be answered at another time.

Therein lies the optimism moving forward — that Duke is bound to have plenty more chances, likely soon, to prove itself in pressure-cooker moments like those shown in front of 16,107 here in Atlanta.

“We’ve got a long season to go,” Duke coach Jon Scheyer said. “I feel more optimistic tonight, losing, than I did even before. Because you find out in this game the character of your team, the heart that they have.

“And this team’s got a lot of heart.”

That much showed, as Duke led No. 19 Kentucky from around the 8½-minute mark of the first half all the way to the final four minutes. And after the Blue Devils lost the lead, they clawed back a couple of times and were in position to regain the lead in the final seconds.

Flagg made a jumper in the lane, the ball bouncing on the back iron so many times it seemed destined to stay there, to tie the game at 72-72 with 1:12 left.

Duke got a stop on Kentucky’s ensuing possession and with 26.5 seconds left — about 7 seconds’ difference on the shot clock — Scheyer took a timeout to put the ball in Flagg’s hands.

After some eye-candy cuts through the lane, Flagg drove and as he spun back to the middle of the lane, he lost the ball into the arms of Otega Oweh, who took it the other way and was fouled by Kon Knueppel.

Oweh made both free throws.

Down two with about 10 seconds left, Duke put the ball back into the 17-year-old’s hands. And again, he turned the ball over — losing control of it in the corner, in front of Duke’s bench, and then slipping to the ground.

“Coach has trust in me to go make a play,” Flagg said. “I’m looking for (the ball) in that moment. It didn’t work out but I’m still going to look for it, no matter what.”

The Blue Devils still had hope, as Lamont Butler made it a 75-72 lead with about 5 seconds left but missed the second free throw. But a missed free-throw box out led to Oweh coming away with the ball, essentially sealing it for the Wildcats.

“Give them credit, tip your hat to them,” Scheyer said. “For us, we’re going to grow and learn from this, I promise you that.”

The lessons probably start with focusing on what the Blue Devils did well in the first half that didn’t carry over through halftime.

Tracking back to that erosion from Duke’s first half to second; the Blue Devils scored 46 points in the first half, at a clip of 1.24 points per possession, while shooting nearly 50% (18-for-37). They did so with a paltry 3-for-12 mark on 3s; the buoy came from a 28-6 advantage in points in the paint, along with an 11-0 margin in points off turnovers and 8-1 edge in fast-break points.

Those things evaporated in the second half. Kentucky outscored Duke 20-18 in the paint in the second half and the Wildcats had a 9-4 advantage in both points off turnovers and fast-break points.

That’s how Duke’s second-half points per possession dwindled to 0.76.

“I think it could have got a little stagnant, at times,” Flagg said of Duke’s second-half offense. “I think a lot of it was defense. There was a lot of miscommunications on defense that led to some easy stuff for them.

“Transition offense is a lot easier than playing in the halfcourt for the whole half. I think we kind of slowed it down a little bit and that led into that.”

Injuries played an inescapable role, here.

On the first possession of the second half, freshman center Khaman Maluach landed awkwardly, all 7-2, 250 pounds of him falling backward onto the baseline. His minutes were sporadic in the second half because of cramps, Scheyer said after the game; he still had 10 points on 5-for-5 shooting, along with seven rebounds and two blocks.

With a little less than 13 minutes left in the game, Duke lost Sion James. The guard took a hard hit on a screen and went to the ground holding his right shoulder; he left the game and didn’t return.

“He took a hard hit on that screen. A hard hit,” Scheyer said after saying he wasn’t sure of the severity. “We’ll get him back and get him evaluated and we’ll see.”

James had a fast-break bucket that put Duke up 56-47 just before his injury, and he was still in the game when Flagg missed two free throws — either of which would’ve given Duke its first double-digit lead of the second half.

Instead, Koby Brea made a 3-pointer on the play that James suffered the injury and the score was tight the rest of the way.

Kentucky landed the first punch, getting three 3s in a 64-second span to take an 18-13 lead less than six minutes into the game. Fifteen of those 18 points came on 3s; as expected for a Mark Pope-coached team.

The next seven minutes were mostly controlled by Duke, though, which is how the Blue Devils slugged their way into a 30-24 lead.

Flagg had eight points in a 17-5 run and exited with 6:40 before halftime after picking up his second foul. Knueppel looked like he was forcing things early but settled in and matched Flagg’s 12 first-half points, scoring all of those in the last 8½ minutes of the first half.

Knueppel finished with 14 points, going 1-for-8 in the second half and finishing the game 5-for-20 from the field. He and Flagg combined to take 39 of Duke’s 71 shots.

TIP-INS: Andrew Carr, the Wake Forest transfer, led Kentucky with 17 points. He had two three-point plays in the final four minutes and assisted on a bucket in between them, which gave the Wildcats their first lead since the first half. … Flagg scored 12 of Duke’s last 14 points; the only ones he didn’t were two free throws by Tyrese Proctor when he was shooting a 3-pointer with 6:30 left. So, Flagg was the only Blue Devil to make a field goal in the game’s final 10 minutes. … Proctor had 12 points, 10 of which came in the first half. Fellow returning guard Caleb Foster had four points on 2-for-9 shooting. … Neither Isaiah Evans nor Darren Harris played for Duke. … Durability has been a strength of James; he missed one game across four seasons at Tulane.