2008-09: Marek Mazanec was the starting goaltender for Team Czech at the U16 World Championships.
2009-10: Mazanec made his debut in the Czech Extraliga, appearing in one game for HC Plzen, and was one of the top goalies in Czech junior hockey playing for the Plzen U20 team. He allowed three goals in one period in his only Extraliga action. He also appeared in three B Extraliga (second league) games on loan to SHC Klatovy and was 2-1 with a 3.24 goals against average. In 43 games for the Plzen U20 team he was 30-13 with a 2.60 goals against and .918 save percentage. Plzen finished first in the regular season before being upset in the playoff quarterfinals. Mazanec and Pavel Francouz played two playoff games each and Mazanec was 1-1 with a 3.50 goals against and .891 save percentage.
2010-11: Mazanec split the season between HC Plzen in the Extraliga and the club's U20 tea. He was loaned to HC Pisek in the Czech B Extraliga late in the season and during the relegation playoffs and competed for the Czech Republic at the 2011 U20 World Junior Championship. In 15 games for HC Plzen, which slipped to ninth in the 14-team league, he was 9-6 with 1 shutout and had a 2.79 goals against and .911 save percentage. He was 3-0 and had one shutout playing for Pisek during the regular season, with a 1.00 goals against and .978 save percentage. In six relegation games he had a 3.29 goals against and .910 save percentage. Mazanec was dominant at the junior level for HC Plzen's U20 team, finishing 18-12 with 7 shutouts and posting a 2.10 goals against and .925 save percentage. In three games for the seventh-place Czech Republic team at the WJC he was 1-2 with one shutout and had a 5.37 goals against and .828 save percentage. Mazanac was ranked tenth amongst European goalies in Central Scouting's final rankings prior to the 2011 NHL Draft but was not selected in his second year of eligibility.
2011-12: Mazanec appeared in 24 games for HC Plzen and spent much of the season on loan to SHC Klatovy in the Czech First Division (third league). He was 12-7 with 1 shutout and had a 2.96 goals against and .900 save percentage in 19 regular season games as a backup to HC Plzen's veteran starter Adam Svoboda. HC Plzen, after finishing second, reached the playoff semifinals . Mazanec played five playoff games and was 1-4 while posting a 2.16 goals against and .919 save percentage. He played 17 games with SHC Klatovy during the season and was 10-7 with a 3.78 goals against. After finishing seventh in the West Division, SHC Klatovy reached the playoff semifinals and in six games Mazanec was 3-3 with a 3.18 goals against. Not among the eleven European goalies in Central Scouting's final rankings prior to the 2012 NHL Draft, he was selected by Nashville in the sixth round (179th overall).
2012-13: The presence of Boston Bruins starter Tuukka Rask in Plzen during the NHL lockout limited Mazanec's appearances in the first half of the season but the opportunity to be mentored by by Rask and veteran Adam Svoboda seemed to elevate Mazanec's game. Mazanec was 9-12 in 21 regular season games with 1 shutout and had a 2.49 goals against and .913 saves percentage. After finishing third in the Czech Extraliga regular season, Plzen defeated second-place Zlin in the playoff finals to capture the league championship. Mazanec started all 20 playoff games and was 12-8 with 2 shutouts; posting a 2.13 goals against and .932 save percentage. Mazanec signed a two-year entry-level contract with Nashville in May 2013.
Mazanec is another typical Nashville late round overage pick, a big size goalie who is athletic and a late bloomer. He has played the last three years in the Czech Elite League. He has been with HC Plzen his whole career so the Czech-born goaltender was very excited to come to play in North America. The tall lanky netminder needs to gain more strength and will have longer timetable to fully develop his raw talents and potential.
Mazanec finished a decent career in the Czech league and he will now head over to North America. After opening the season in the AHL, Mazanec was called upa nd has performed well at the NHL level for the Predators.