Scaloni confirmed Messi has recovered from a recent muscle strain and is in line to feature from the start against Algeria in their opening Group J match on Wednesday at the 2026 FIFA World Cup.
"Not only Argentines, everyone wants to see him on the pitch, wants to see him play," Scaloni said. He added that Messi "has always been fundamental for us. And now even more so."
Messi, 38, did not start Argentina's recent friendly win over Honduras, which ended 2-0, but came off the bench in a 3-0 victory over Iceland, scoring from the penalty spot to show he remains decisive in front of goal.
The Argentina captain is set to appear at a record sixth World Cup, underlining his longevity at the top level. Scaloni dismissed any suggestion that Messi's presence could be a burden on the squad, insisting his influence has remained constant regardless of physical condition or opposition.
Long-time teammate Nicolas Otamendi also spoke about Messi's impact as the squad prepares for another major tournament. The defender, who is also expected to be part of a final World Cup campaign, described Messi as "the best player in history."
"We have lived many beautiful moments together," said Otamendi. "He is a simple person, but a competitive animal. That pushes you to keep trying, to support him and help him."
Argentina, reigning world champions after their 2022 triumph, will also face Austria and Jordan in Group J as they look to defend their crown.