Enzo Pérez's call-up as a last-minute replacement in the Argentina squad has made the Albiceleste the oldest team at a second World Cup in a row, with an average age of 29 years, six months and 24 days.
River Plate midfielder Pérez, 32, flew out to Russia after 25-year-old Manuel Lanzini injured his knee, pushing Argentina past Costa Rica as the oldest squad by a single day.
The Albiceleste also had the oldest squad in Brazil four years ago, when they finished as runners-up to Germany, with an average age of 28 years, 11 months and six days.
At 36, Chelsea goalkeeper Willy Caballero is the eldest member of the squad, two years older than Javier Mascherano, while Giovani Lo Celso and Cristian Pavón are Argentina's youngest players, both 22.
The national team squad has become quite the attraction in Russia, with around 400-500 eager fans turning out to catch a glimpse of Lionel Messi and his team-mates.
At an opening training session on Monday, a particularly affectionate welcome was reserved for the Barcelona forward, as hordes of adoring young supporters chanted "Messi, Messi" on his way out for an hour-long practice.
After several days of chilly temperatures in the Russian capital, overcast skies gave way to sunshine, with excited locals packing a temporary stand in Bronnitsy, southeast of Moscow, to follow the action.