Both teams have exceeded expectations by making it to the last four in Russia and are now just one match away from the showpiece final.
England are competing at this stage for only the third time in their history, and a first in 28 years, while Croatia's best finish was in 1998 when coming third.
Mandzukic believes that his side's current crop of players have a nice blend of experience and youth, but is unsure whether it will be enough to get them past the Three Lions in Moscow.
"Croatia, maybe, have several more experienced players but we also have great young players. That is what makes us good," he told reporters.
"I would say the chances in the game are 50/50 because everyone deserves to be the in semi-final. There is no fear from our side, we respect everybody; however, we believe in ourselves."
England have won four, lost two and drawn one of the eight previous meetings between the two sides.