I'am not worried at all. Pereira can catch him, mainly in later rounds if Jiri slows down...but still, there is much more ways for Jiri to win and dominate in this fight than for Pereira.
+ there is more of not very known and debated stuff outside of our region
- Jiri should be better in every aspect of his fighting game, mainly ground, it should be on same level as his standup (he +- 1.5 year ago hired BJJ expert into his trainers team) and he is reportedly in best form of his
life recording to big circle of people.
- Jiri's main sparring for +- decade was lefthanded ranked GloryKickboxing fighter with similiar height and bigger reach
- His doctor said that he never seen someone fully and fast recover without any major consenqueces like Prochazka. His arm is more like improved than damaged because of untreated ruptures which were fixed after xxx years.
Jiri simply have to hold distance during stand-up and eventually take it down if there will not be holes in Pereira's stand up for finish.