After training for four years and attaining the rank of second dan black belt, which he earned by completing a twenty-man kumite among other tests, he returned to the Czech Republic and opened his own Kyokushin dojo in August 2005.

Following this, he was recruited by K-1 and returned to Japan to train under Jayson Vemoa at the Ichigeki Academy where his sparring partners included Glaube Feitosa, Takumi Sato and former foe Ewerton Teixeira.

[6] In his third and final outing in the promotion, Soukup lost to Mladen Brestovac by way of unanimous decision after being knocked down with a third round knee strike in the tournament reserve match at the K-1 World Grand Prix 2010 in Bucharest in Romania on May 21, 2010.

[7] Soukup lost his second fight in a row when he dropped a unanimous decision to Jhonata Diniz after surviving knockdowns in rounds one and three at Ichigeki Brazil 2010 in São Paulo on July 31, 2010.

[9] He had a close fight with Fabiano Cyclone in the quarter-finals but scoring a knockdown in round two was enough to earn him the nod via majority decision and advance to the semis where he faced Makoto Uehara.