Pietras began his professional career with the Philadelphia German-Americans of the American Soccer League in 1933.
He spent five seasons with Philadelphia, winning the 1935 league title and the 1936 National Challenge Cup championship.
His first game was a U.S. victory over Mexico, 4–2, in a World Cup qualifier.
[3] In 1936, Pietras was selected for the U.S. soccer team which competed at the 1936 Summer Olympics.
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