Career
Mazanec was selected by the National Hockey League (National Hockey League)"s Nashville Predators in the sixth round, 179th overall, of the 2012 National Hockey League Entry Draft. Mazanec played at the junior level with Immunohistochemistry Písek, before at 14 moving to The Human Context Plzeň, where he continued his junior career. Beginning in the 2009-2010 season, he played at the senior level in the professional Czechoslovakian Extraliga.
On May 3, 2013, the Nashville Predators of the National Hockey League signed Mazanec to a two-year, entry-level contract.
He began the 2013-2014 season with the Predators" American Hockey League (AHL) affiliate, the Milwaukee Admirals. On November 8, 2013, Mazanec made his National Hockey League debut with Nashville, playing 51:37 and allowing two goals on 24 shots after replacing starter Carter Hutton in a game against the Winnipeg Jets.
After 10 games with the Predators he posted a.932 save percentage and was named National Hockey League Rookie of the month for November.