Suddenly there were two popes in the Popemobile: after mass on Sunday, Leo XIV met a boy dressed as a "little pope" in St Peter's Square.
Leo invited him to join him in the Popemobile and posed for photos with the child.
Afterwards, the two spoke a few words with each other.
The boy wore a handmade mitre on his head and a red chasuble over his jumper.
The encounter was widely shared and commented on online.
Dressed-up children - whether as mini popes or mini bishops - appear at papal meetings from time to time.
In October, Leo XIV met a large group of "student cardinals" and "Pope Augustine" in Rome.
The pupils came from a Catholic school in Chicago and had elected a "mini-pope" in a children's conclave in May.