That defense brought out the worst in a Casey team that has struggled to score all season. The Rebels went 4-for-24 from the field in the second half, while host Lincoln overcame a sluggish first half on offense to outscore Casey 36-18.
"We had a great second half on both ends of the floor," Lincoln coach Jeff Jackson said.
That was enough to put top-seeded Lincoln (16-11) into Friday's title game against third-seeded Boyle County and into next week's 12th Region Tournament.
The first half had played out well for Casey (8-20), which led or was tied with Lincoln for nearly 11 of the 16 minutes.
"In the first half we shot the ball well," Casey coach Shawn Conley said. "The pace of the basketball game was to our liking, and we were able to move the ball. In the second half we struggled."
Conley said that was due in part to the way Lincoln defended at the start of the second half.
"Lincoln County did a pretty nice job defensively," he said. "They didn't change anything, but they did a better job getting through screens and putting pressure on us."
"I thought we got better defensively," Jackson said. "That's something we talked about at halftime, staying solid and getting pressure away from the basket."
Casey didn't score until the 5:30 mark of the third quarter, then went another 3:02 before its next basket.
By then, Lincoln had taken a 36-22 lead, making things tough for a Casey team that was held below 50 points in 16 of its 28 games.
"I just knew if we fell down by 10 or 12 it'd be tough for us to come back," Conley said.
The fourth period looked a lot like the third, as the Rebels went scoreless for the first 4:11 as Lincoln stretched its lead to 51-30.
Casey shot 24.4 percent for the game
Casey's 16.7 percent shooting in the second half lowered its overall mark to 24.4 percent (11-for-45).
Lincoln took the opposite course on offense, shooting 42.2 percent (19-for-45) after an 8-for-26 first half.
The Patriots' best shooting came in the third quarter, when they were 7-for-11, and they started the second half by turning inside to center Jonathan True.
True, who led all scorers with 21 points, scored their first two baskets, and he scored eight points and Nathan Norman got four during their 12-2 run.
"He got the ball down on the block and connected on that," Conley said. "That was obviously what we didn't want. We wanted him to catch the ball about 10 feet away from the basket."
Jackson said he was pleased with the overall efficiency of the offense led by freshman point guard Reed.
"I thought Kelly had a super ballgame at the point," Jackson said. "We moved the ball at times in the second half probably as well as we have any time all season. We had great ball movement, and we got the ball where we wanted it."
Reed and Norman had nine points each for Lincoln, and True had a game-high 12 rebounds.
Now Lincoln turns its attention to a rubber game with Boyle, which won their last meeting 62-47 on Jan. 23.
"They got off to a great start, and we didn't," Jackson said. "They're well-coached, and they're very physical. We've got to keep our focus, and we've got to play defense and rebound."
Meanwhile, the season is over for Casey, which had half of its victories in the books by Dec. 23, when it won a tournament in Gatlinburg, Tenn.
After that, the Rebels were hurt by injuries and departures. Leading scorer Derek Vest, who had a team-high 12 points Wednesday, missed eight games, and junior forward Ben Barlow was forced to miss the district game with a flu-like illness.
"When we got back from Gatlinburg, it wasn't very often from then on out that we played with the same kids who won that tournament," Conley said.
CASEY (8-20) - Derek Vest 12, Keith Price 5, Dustin Johnson 7, Charlie Fox 4, Josh Patterson 2, Will Johnson 5, Corey Dial 2.
LINCOLN (16-11) - Matt Reynolds 6, Nathan Norman 9, Jonathan True 21, Kelly Reed 9, Chris Hart 8, Ryan Weller 2, John Henry Russell 5.