The Croats stunned the tournament favorites in the quarter-finals with a vintage performance, after going a goal down in extra-time but digging deep to bounce back and force a penalty shootout that they ended up winning.
While their elimination of the five-time world champions was largely unexpected given Brazil's form, it was still a classic Croatian achievement.
With a never-say-die attitude, even when the odds were stacked heavily against them, disciplined Croatia are now deservedly in their second straight World Cup semi-final, and underestimating them would come at Argentina's risk.
Playmaker Luka Modric has been their driving force at the age of 37, a motivation for everyone else in the squad.
With no players suspended and no injury concerns following the return of defender Borna Sosa, Zlatko Dalic's team is brimming with confidence and ready for more.
Super-sub Bruno Petkovic, who scored the equalizer against Brazil, could earn back his starting spot over Andrej Kramaric while Mario Pasalic is expected to keep his in attack.
The Argentines, looking for their first World Cup title since Diego Maradona's 1986 team, have their work cut out.
Defenders Marcos Acuna, a starter, and Gonzalo Montiel are suspended because of bookings, limiting coach Lionel Scaloni's options at the back.
Nicolas Tagliafico could come on to replace the former but it will be a less attacking formation, with wingback Acuna having added more spark to the team.
Missing title
A question mark also hangs over veteran Angel Di Maria and his fitness, with the 34-year-old having largely been used as a substitute in the tournament despite recovering from injury.
Messi, at 35, playing likely his last World Cup, is desperate to land the one major title missing from his extensive collection but he is also carrying the weight of the nation on his shoulders.
The comparison with Maradona for the title of the greatest Argentine player of all time cannot be complete without a world title, which the late Maradona won almost single-handedly 36 years ago.
They almost did not make the semi-finals after the Dutch came from 2-0 down to score twice late in the game and force extra time and penalties in a bad-tempered encounter.
A repeat of a shootout, this time against mentally tough Croatia, must be a terrifying prospect for Scaloni's men even though keeper Emiliano Martinez rose to the occasion against the Netherlands, saving two spot kicks.
Croatia came through two shootouts and extra-time to reach the 2018 final before losing to France and have gone to penalties in both their knockout stage matches in Qatar to boast a 4-0 perfect record. Based on that statistic, another one against Argentina would most likely carry them into the final.