Results from the second game of the doubleheader were not available at press time.
Sikeston (12-9) led the entire game only to give up six runs in the top of the seventh inning to Mayfield.
Post 114 surrendered four walks, a hit batter, four hits in the inning and numerous passed balls.
"We got on top of them and we just sat on the lead," said Sikeston coach Todd Baker. "It all comes down to throwing strikes and we didn't do that late in the game. They mixed a couple hits in there, but the walks are what got us."
"We thought we were done," said Mayfield assistant Jim Melton. "Then all of a sudden we were getting baserunners and I thought, 'we're still in this thing.'"
Post 26 scored two runs on passed balls, a hit batter brought in another run, and then an RBI-single tied the game.
Another walk brought in the go-ahead run.
Then Nathan Brown doubled home an insurance run, although Post 114 got out of the inning with a unique double-play as two runners were tagged out at home plate simultaneously.
The loss cost a strong effort by pitcher Zach Friend, who threw 4 2/3 innings and allowed one hit and two runs.
"Zach threw a heck of a game -- I hate not getting the win for him," said Baker.
Sikeston had one last chance to win the game in the bottom of the seventh but Post 114 could only muster one run.
Baker felt he made a managerial error when he tried a double-steal that resulted in Seth Baker getting thrown out at third.
The very next batter, Josh Stevens, singled home Josh Jackson from second.
"We had our opportunities and I ran us out of a big one in the last inning," said coach Baker. "We were just trying to do too much and it cost us."
Stevens went 3-4 to lead Sikeston. Williams was 2-4 with three stolen bases. Seth Baker went 1-2 with two RBIs. Josh Pierce was 2-3 with two runs and Friend also collected a hit.
Sikeston won't play again until the Paragould Tournament July 6-8.