Tenkrát began his pro career with his local club HC Kladno in 1994-95, playing a single game with the senior squad; he would then keep playing regularly with the senior squad from next season on, until he was drafted by the Anaheim Mighty Ducks in the eighth round of the 1999 NHL Entry Draft, 230th overall. He spent the 1999-00 season in the SM-Liiga with HPK Hämeenlinna and Ilves Tampere before leaving for North America. He would play from 2000 to 2002 in the American Hockey League and the NHL for the Ducks and the Nashville Predators before returning to Europe to join Kärpät Oulu of the SM-Liiga and Khimik Voskresensk of the Russian Superleague.
He made a comeback in North America in 2006, after the Toronto Maple Leafs, who detained his rights, traded them to the Bruins. He started the season with the AHL's Providence Bruins, but got called up later in the season.