The 21-year-old Banik Ostrava player has been in England since Tuesday in a bid to finalise a one-year loan deal with a view to a permanent move and he will soon be a Bolton man barring a late hitch.
"Gregus' move to Bolton is 90 per cent done and only an administrative issue can ruin it," Banik official Michal Dyml told Czech newspaper Blesk.
"I cannot reveal any details from this deal. But if the player should stay at Bolton beyond the first year, then we would reach more interesting figures."
The captain of the Slovakia under-21 side impressed Bolton manager Dougie Freedman during a match against Romania.
The player himself added: "The coach saw me in the match against Romania and wanted me to come. I am not interested in joining any other clubs."
He also told Sport in Slovakia: "The facilities at Bolton are superb. The training centre is top class but that's something they are used to here, I guess.
"The stadium is just beautiful and I'm looking forward to my new spell.
"I'm happy. If someone had told me during the autumn that I would be at a Championship club in the spring, I would not have believed it."