Srna's father passed away during Croatia's opening 1-0 Group D win over Turkey on Sunday and the right back rejoined the squad after travelling home for Monday's funeral.
"It is a very difficult moment for me and my family and after talking to them, I decided to return to France," he told a news conference on Thursday ahead of the match in St Etienne.
"It was my father's last wish. He invested everything he had in my career and I wouldn't be here if it hadn't been for him.
"I have to be strong and shift my focus on what lies ahead. The travel won't be a factor as I also flew to a friendly against Austria in May 2010 the day after my wedding."
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The Czechs are under pressure after losing their opening match to holders Spain 1-0 and Srna believes the situation could play into his team's hands.
"They will have to come forward and that should give us room to operate," he said.
"The Czechs have a very gifted player in Tomas Rosicky, who is their version of (versatile Croatia and Real Madrid playmaker) Luka Modric.
"They're a disciplined and tactically proficient team but I think we are the better side.
"On paper, this Croatia team is better than the one that reached the 1998 World Cup semi-finals in France, but that doesn't mean we will emulate their success.
"Football is unpredictable and there are no clear favourites here in what has been a very balanced tournament."
(Writing by Zoran Milosavljevic; Editing by Toby Davis)
