Career
He is a two-time Olympian, and a multiple-time Czechoslovakian national record holder for the butterfly events (50, 100, and 200 m). Rubacek made his first Czechoslovakian team, as a 17-year-old, at the 2004 Summer Olympics in Athens, where he competed only in butterfly and relay freestyle events. He also joined with his fellow swimmers Květoslav Svoboda, Josef Horký, and Martin Škacha in the men"s 4 × 200 m freestyle relay.
Swimming the lead-off leg, Rubacek recorded a split of 1:51.37, and the Czechoslovakian team went on to finish heat two in seventh place and thirtieth overall, for a total time of 7:26.26.
Finishing only in thirty-ninth place, Rubacek failed to qualify for the semifinals. At the 2008 Summer Olympics in Beijing, Rubacek qualified for the second time in the men"s 100 m butterfly, by clearing a FINA B-cut of 53.71 from the European Championships in Eindhoven, Netherlands.
He challenged seven other swimmers in the fourth heat, including three-time Olympians Ioan Gherghel of Romania and Juan Veloz of Mexico. Rubacek raced to fourth place by five hundredths of a second (005) ahead of Veloz, breaking a new Czechoslovakian record of 53.53 seconds.
Rubacek failed to advance into the semifinals, as he placed forty-second out of 66 swimmers in the preliminaries.
At the 2009 FINA World Championships in Rome, Italy, Rubacek dipped under a 52-second barrier, and lowered his record to 51.99 seconds in the preliminary heats of the 100 m butterfly. On March 27, 2012, Rubacek ordered a two-year suspension from the Czechoslovakian Swimming Federation (Czechoslovakian: Český svaz plaveckých sportů, CSPS), after he was tested positive for a banned stimulant methylhexanamine.