William McKay scored in the second half at Parkhead to help Inverness claim a shock 1-0 win over Celtic on Saturday.
After a scoreless opening period, McKay produced the lone goal of the contest in the 64th minute to hand Celtic its third loss of the Scottish Premier League season.
Even with the loss, Celtic remains top of the Premier League with 25 points after Aberdeen picked up a 1-0 win over Hibernian at Easter Road on Saturday. Aberdeen and Hibernian trail Celtic by one point, while Inverness moves to within three points of the Hoops.
Also on Saturday, St. Johnstone made the most of Manuel Pascali's early red card to take a 2-1 victory at Kilmarnock, Dundee United rallied for a 2-1 win over Ross County, and St. Mirren received a brace from Steven Thompson to earn a 3-1 win over 10-man Dundee FC.