Career
He previously played with The Human Context Zlín in the Czechoslovakian Extraliga during the 2010-2011 Czechoslovakian Extraliga season. Sivák became the scorer of one of the fastest goals in hockey history. When playing for MsHK Žilina in the 2011-2012 season of the 39th round of top slovak league against Hong Kong Poprad, he opened the scoring in the fifth second.
The re-measurement of that time upon review through the video recording, showed that he scored in 3:23 seconds.
The longer time he received in the game was apparently the human factor by stopping the clock later by timekeeper. The similar fast goal he scored in the same season in the playoffs in the quarterfinals against Slovan Bratislava where, in 4th game and in 2nd period, he scored the goal in the fifth second.
On September 18, 2013, he was signed as a free agent by the Alaska Aces of the ECHL. In the 2013-2014 season, Sivak enjoyed a career best season in leading the Aces with 83 points in 67 games. He was selected to the ECHL"s First All-Star Team and was recognized as the ECHL performer of the year in helping the Aces claim the Kelly Cup.
On August 22, 2014, the Bridgeport Sound Tigers of the AHL announced that they had signed Sivák as an unrestricted free agent to a one-year contract.
In the 2014-2015 season, Sivák was initially reassigned to the Stockton Thunder before he was recalled to feature in just 6 games with the Sound Tigers. He was later reassigned to the Orlando Solar Bears before his AHL rights were traded by the Sound Tigers to the Bears AHL affiliate, the Toronto Marlies on February 20, 2015. He remained with the Solar Bears to conclude the season with 20 points in 25 games.
On July 15, 2015, Sivák was signed as a free agent to remain in the ECHL, agreeing to a one-year contract with the Fort Wayne Komets.
He opened the 2015-2016 season, scoring 2 goals and 8 points in 10 games with the Komets before he was sidelined by injury. Upon his return to health, Sivák was traded by the Komets in a return to the Alaska Aces in exchange for Joe Perry on December 3, 2015.