At the start of the game Caley Thistle had not conceded a single goal this season, however, that record was shattered in a disappointing 90 minutes at Firhill.
Inverness started well and took the lead through Aaron Doran but Thistle hit back with Stevie Lawless equalising after 19 minutes and, just four minutes later, Abdul Osman headed home to give the hosts the lead.
Kallum Higginbotham added a third goal Thistle goal in the second half and the hosts could even afford for Kris Doolan to miss a late penalty as they secured the points.
VIDEO: Highlights of Partick Thistle 3-1 Inverness Caley Thistle