The high-class career of attacker Karl-Heinz Mosakowski began at the age of 20 at VfL Bochum in 1949/50 in what was then the 2nd League West. In his debut year in the second division, the striker scored nine goals in 25 association games and VfL came in 12th. After three rounds with a total of 64 round games and 22 goals, the "Mosa" called offensive player moved to southern Germany and joined ASV Durlach in the 2nd South League for the 1952/53 season. In the third year in Karlsruhe, 1954/55, the team from Durlacher Turmbergstadion rose from bottom of the table in the amateur camp in North Baden and Mosakowski moved together with his offensive colleague Karl Brunn in the Nahe valley to Eintracht Kreuznach in the first-class Oberliga Südwest.
The first game in the Oberliga Südwest completed "Mosa" on August 28, 1955 in a home game against FK Pirmasens. In the surprising 4: 1 success, he introduced himself with two hits. At the end of the round, the striker had played all 30 rounds and scored 21 goals. He finished 3rd in the Südwesttorschützenlister behind Horst Schmutzler (30 goals) and Willi Wenzel (23 goals). 1. FC Kaiserslautern won the championship ahead of TuS Neuendorf and Kreuznach came in eighth. In his second round at Eintracht, the 2: 1 home win on December 8, 1957 stands out against the "Red Devils" from Betzenberg, who competed with Friedel Späth , Karl Schmidt , Horst Eckel , Fritz Walter and Ottmar Walter , among others . Mosakowski scored both goals against the "Walter-Elf" at the Heidenmauer. From 1955 to 1958, the goal-scoring attacker in Kreuznach made 85 league appearances in which he scored 45 goals. For the 1958/59 season he moved to the "Deutsche Eck" in Koblenz to join the league competitor TuS Neuendorf. In addition to teammates like Günther Kasperski and Otto Hölzemann , the newcomer from Kreuznach in the summer of 1959 could not prevent relegation to the 2nd Southwest League. Immediately succeeded with the runner-up in 1959/60 the league return. With two missions and one goal - the home games against Phönix Ludwigshafen (4: 1) and 1. FC Saarbrücken (0: 3) - he ended his high-class career after the 1960/61 season.
Hardy Grüne , Lorenz Knieriem: Encyclopedia of German League Football. Volume 8: Player Lexicon 1890–1963. Agon-Sportverlag, Kassel 2006, ISBN 3-89784-148-7 .