The young, tall Slovakia U21 midfielder joined Bolton Wanderers in the winter of 2013 on a year-long loan with option to buy from his parent club, Banik Ostrava in the Czech Gambrinus Liga. Gregus slotted straight into the reserve team and became a fixture for the U21 team in the second half of the 2012/13 campaign. The central midfielder was finally utilized by Dougie Freedman during Bolton's 2013/14 pre-season, starting in the Trotters' opening match against Rotherham United.
Gregus has international experience with Slovakia at the U19 and U21 levels. Gregus scored an absolute stunner of a goal in his reserve team debut, a 3-3 draw at Manchester City. The goal was a wonderful long-range strike that smacked the underside of the bar on its way to beating the City goalkeeper. He has not made his first team debut yet.