Croatia, runners-up four years ago, started their World Cup campaign with a goalless draw against a well-drilled Morocco at Al Bayt Stadium.
Only four players from their final defeat by France in 2018 started this game and they lacked an attacking spark throughout, but came closest through Nikola Vlasic’s toe-poked effort.
Morocco were impressive, but failed to create clear-cut opportunities.
Belgium play Canada in the other Group F game at 19:00 GMT on Wednesday.
Croatia, who are 12th in Fifa’s world rankings, dominated possession as expected, but they were unable to create opportunities or break down Morocco, who have only lost two of their past 40 games across three years.
Croatia will play Canada in their next match on Sunday (16:00 GMT kick-off), while Morocco face Belgium on the same day (13:00).