A superb strike from skipper Sean Welsh shot Caley Thistle first in the Championship with their 1-0 win over Kilmarnock knocking their opponents from top spot.
The second half screamer settled a close contest and put ICT two points clear of Killie and Raith Rovers, who are at promotion rivals Arbroath tomorrow.
A second victory of the campaign over the title favourites sends out a warning shot to the doubters reading too much into their dip in form, results-wise at least.
This was the third game of the week for both teams, with the showdown being screened live on BBC Scotland.
Caley Thistle were knocked out of the SPFL Trust Trophy on penalties against Raith Rovers on Tuesday, following on from their 1-1 home draw with Scottish Cup third round tie against Morton at the weekend.
Killie arrived in the north on the back of two victories. They edged past Queen’s Park 1-0 in the Scottish Cup on Saturday then, after making 1o changes, scored two late goals in a 3-2 SPFL Trust Trophy quarter-final triumph at Hamilton on Tuesday.
Usual starters return to the fold
ICT, who made six changes for their last eight tie with Raith, were back to familiar lines. Skipper Sean Welsh was the only newcomer to the side which played Morton last Saturday.
For Kilmarnock, who lost 1-0 to ICT in August, they also returned mainly the team which won in the Scottish Cup.
Billy Dodds’ hosts haven’t been turning positive play into points, with only one win in eight.
Kilmarnock, whose last win at the Caledonian Stadium came in 2010, have lost at home to all their main promotion rivals this term, but are the best away team in division.
The teams wore armbands in memory of Jessie Wilson, mother of Barry, the assistant manager of ICT and wife of former Ross County boss Bobby Wilson, who died earlier this week.
Front-foot approach from Caley Jags
Inverness were quick out of the traps and a diving header from Shane Sutherland flashed wide as he met an Aaron Doran delivery.
It was all Caley Thistle early on as they pinned Killie back, looking for the breakthrough to gain control of the scoreline.
A swift counter-attack cut Killie open on 12 minutes and it ended with Zach Hemming saving Billy Mckay’s effort after the striker was put through by MacGregor. Smart play.
Kilmarnock got their first sight of goal after a few neat passes landed at the feet of Rory McKenzie. His 25-yarder was pushed behind by Mark Ridgers, with the wet surface preventing him holding it.
The hosts were almost in front on 29 minutes when a swerving shot from Sutherland whipped around the left post after grafting work on the box by Welsh ended with him being tripped and the forward hitting the follow-up shot.
There was plenty of effort from all players after the break and former Ross County forward Oli Shaw was not far off with a stinging drive which had Ridgers watching all the way.
The magic moment for Inverness came on 69 minutes when Allardice skipped in from the left flank, teed up Welsh and the skipper unleashed an unstoppable shot high past Hemming into the net.
It was his fourth goal of the season and he may not score as many with such importance this term.
Inverness were looking to finish the job and full-back Robbie Deas, who had a strong game, unleashed a stinging shot, but it lacked the accuracy to match the power.
Substitute Fraser Murray’s late free-kick offered potential for Killie, but he flighted it too high to concern Ridgers.
ICT can head head for their double-header in Greenock with an extra spring in their step next week.
They are face Morton in the Scottish Cup replay on Tuesday then return to Cappielow for days later on the hunt for more league points.
HOW THEY LINED UP
CALEY THISTLE (4-4-2) – Ridgers 6, Welsh 7, Deas 6, Devine 7, Carson 6, Mckay 6 (McAlear 84), Doran 6 (Harper 76), Sutherland 6, MacGregor 6 (Walsh 61), Broadfoot 6, Allardice 7. Subs not used: MacKay (GK), Jamieson, McDonald.
KILMARNOCK (4-4-2) – Hemming 6, Hodson 6, Euan Murray 6, McKenzie 7 (Alston 69), Shaw 6, Robinson 6 (Burrell 78), Lyons 6, Waters 6, Polworth 6 (Fraser Murray 71), McGowan 6, Burke 6. Subs not used: Walker (GK), Stokes, Armstrong, Sanders.
Referee – Nick Walsh.
Attendance – 2296.
Man of the match – Sean Welsh.