After the final whistle, unsavoury scenes marred the fixture, with some fans invading the pitch to taunt Pep Guardiola's players while they trudged off the field.
Video footage showed Aguero lashing out at one supporter and had to be restrained following a confrontation.
Now, it has been claimed by journalist Jose Alvarez Haya that Aguero was spat at by the supporter, sparking the hitman's rage.
The reporter told ChiringuitoTV: "A fan spat at Aguero and Kun feared he might have an object to cause him harm."
Wigan have launched an investigation into the post-match scenes.