Coulson picked a perfect time for his first, and it came at the expense of the Jackson Post 158 Senior American Legion baseball team.
Coulson fired a three-hit gem Friday to help Creve Coeur Post 397 blank Jackson 6-0 in the opening round of the Zone 4 tournament at Capaha Field.
"He threw well," Jackson coach Mark Lewis said. "We've been swinging the bats well, but he did a good job. He kept us off balance."
Jackson piled up 34 runs in three games last week to win its first District 14 title since 2005 and just its second in program history.
But the Post 158 offense was no match for Coulson, a 2012 Parkway Central High School graduate who was a first-team all-Suburban South Conference pitcher but does not plan to play baseball in college.
"Keith's been one of our top guys all year," Creve Coeur coach P.J. Arway said. "We knew we had him set to go the first game. He did a great job. He located all day."
Coulson struck out 11, walked one and hit two batters. He rarely was in trouble. Jackson placed more than one runner on base in an inning only one time.
"It was very exciting," Coulson said about his first nine-inning performance. "Location and getting ahead early in the count was really the key.
"I relied on my slider a lot and my fastball. I kept my pitch count down . ... I didn't feel too bad at all."
Jackson's (36-16) only serious scoring threat came in the bottom of the sixth inning when an error and a hit batter put runners on first and second with one out. But Coulson got an infield pop fly and a ground out to escape damage.
"I got a little nervous in the sixth, but he settled in and did everything he was supposed to do," Arway said.
Jackson ace Cody Heisserer allowed just one hit through five innings, although Post 158 trailed 2-0. Dan McCune's two-RBI single in the third inning came after a hit batter, walk and sacrifice.
Creve Coeur (32-12) knocked out Heisserer and broke open the game with a three-run sixth inning that included five hits. Jordan Goldenberg had an RBI double, while Matt Hresko and Andrew Childs added RBI singles.
Lucas Mueller's RBI single in the seventh inning rounded out the scoring.
Heisserer allowed five runs, four earned, on five hits over 5 2/3 innings. He struck out two, walked two and hit a pair.
Caleb Rowald allowed a run on four hits in one inning. Adam James pitched 2 1/3 scoreless innings. He gave up two hits and struck out two.
Cody Harris had two of Jackson's three hits.
Chase Simmons doubled, but the catcher had to leave the game in the seventh inning when he ran into a wall along the backstop fencing while trying to catch a pop foul. He was back in the lineup later that night for Jackson's next game.