The Banik Ostrava ace impressed Bolton boss Dougie Freedman and his coaching staff during a training stint at the Championship club.
Banik Ostrava official Michal Dryml has confirmed they are in talks with Bolton over a loan move with a view to a permanent deal.
"I can confirm that we have indeed been in negotiations with Bolton," Dryml told isport.blesk.cz.
"At the moment we are discussing the possibility of a loan with the option of a permanent move.
"It is not that we would announce tomorrow that Jan is leaving tomorrow, but it is very likely that he will be playing in England in the spring.
"Gregus is a very talented young player but he was not getting many opportunities in the autumn part of season, so we are not going to stay in his path. England is England."