Partick Thistle boss Alan Archibald watched in frustration as his side gave Inverness a three-goal lead in a "strange" game which ended 3-2 to the home side who went top of the Ladbrokes Championship.
Goals from Jordon White, Shaun Rooney and Sean Welsh, the latter netting from the penalty spot, had Caley comfortably in front.
The Maryhill side were awarded their own spot-kick but Mark Ridgers saved Miles Storey's effort.
Blair Spittal pulled a goal back with eight minutes remaining before Kris Doolan added a second in injury time.
Archibald told Thistle's official website: "It was a strange game, overall. We started on the front foot as the better team which was exactly what we'd asked for from the players but then they go up and score with their first attack.
"It's bad defending on our part and then they just grew from there.
"In this league, you can't afford to give anyone any sort of head start, never mind a three-goal one and that's what has cost us in the end."
Inverness's first home victory of the season took them one point ahead of Ross County and Ayr United.
Highland rivals County relinquished top spot with a goalless draw away to Queen of the South.
Ayr United came from 2-0 down to beat Falkirk 3-2 and leave the Bairns still looking for their first points of the season.
The visitors were leading at the break through goals by Zak Rudden and Deimantas Petravicius.
Lawrence Shankland reduced the deficit in the 48th minute with a drive and Andy Geggan levelled before an own goal by goalkeeper Leo Fasan, when the ball hit his back at a corner kick scramble, gave the home side all three points.
Bairns manager Ray McKinnon told FalkirkTV: "We contributed to our own downfall, there is no doubt about that.
"To be 2-0 up and then to lose the goals so quickly after half-time is really disappointing."
Fraser Fyvie's stoppage-time strike gave Dundee United a point against Morton.
Michael Tidser had given Morton the lead from the penalty spot in the 11th minute after Rachid Bouhenna fouled Gregor Buchanan.
Fyvie came off the bench in the 73rd minute for Adam Barton to make his first Championship appearance since a December knee injury and he fired in the equaliser.
Dunfermline Athletic fought out a 0-0 draw against Alloa Athletic to remain in eighth and ninth place respectively.
Manager Allan Johnston told the club's official website: "Both teams probably cancelled each other out. I can't remember too many saves by either goalkeeper.
"Obviously it was good to get a clean sheet but we have to do a lot better going forward with the creative players that we have got."
