For Koulibaly, joining the Senegal squad is something of an interesting decision. Though he's of Senegalese descent, he was born in France after his parents left Africa. In fact, Koulibaly played his whole youth international career for France, with 11 U20 caps earned before he moved to Genk in Belgium back in 2012. Koulibaly had yet to get much more than vague consideration at the senior level for France, though, so apparently he decided that it was in his best interest to accept a callup from Senegal.
The African squad will have a chance to cap-tie him at the international level right away, with a competitive match on September 5th against Namibia in Group K of African Cup of Nations qualifying. With only Cheikh Mbengue locked-in as a starter on the backline for Senegal and none of their other central options looking terribly impressive, Koulibaly stands a good chance of starting that match, as well as their friendly against Mauritania on the 12th.
Insigne's callup comes by way of an injury replacement, after Sebastian Giovinco was felled by a muscular issue this past weekend while playing for Toronto in MLS. Insigne had a strong preseason for Napoli in his new trequartista role and played well against Sampdoria on Sunday, but how Antonio Conte plans to use him is so far unknown.
Italy need Insigne -- and the rest of the squad -- to play well, as they face to Euro 2016 qualifiers, on September 3rd against Malta in Florence, and on the 6th against Bulgaria in Palermo. If they win both matches and other results go their way, they can secure direct qualification to the European Championship in France. If they lose both and other results go against them, though, they could fall out of the top three and risk failing to qualify since there are just two more qualifiers after this month.
Outside of those two, Napoli's internationals are the usual suspects, though Gonzalo Higuain was held back from Argentina duty thanks to a fever that left him unable to make the trip to his national team's matches in the United States.