"Leo will come on later and I've already confirmed the team, but we’re going to announce it tomorrow," Scaloni told reporters on Friday.
Argentina, the reigning world champions, have already sealed top spot in Group J after wins over Austria (2-0) and Algeria (3-0).
The captain Messi, who turned 39 on Wednesday, has scored all Argentina's goals so far at the tournament in North America to become the leading scorer in World Cup history.
With Argentina into the last 32 and debutants Jordan already eliminated, Scaloni is expected to ring the changes.
Argentina will face the team that comes second in Group H, which comprises Spain, Uruguay, Cape Verde and Saudi Arabia.