GARY Warren's goal gave Caley Thistle their first success in Perth for three years as they defeated St Johnstone 1-0.
There were two changes from the Inverness side that had overcome Stranraer 2-0 in a Scottish Cup fifth round replay on Tuesday.
Aaron Doran, who came off the bench to score against vthe Scottish League One side, returned, as did fellow winger Marley Watkins. Nick Ross and James Vincent both dropped to the substitutes bench.
Caley Thistle were looking to end a run of five games without a win at McDiarmid Park and they started brightly.
Warren should have done better than send a diving header from Greg Tansey's cross wide when unmarked, before Billy Mckay was foiled by Alan Mannus after being set up by Marley Watkins.
St Johnstone slowly got themselves back into proceedings and only a fine save down to his right by Dean Brill kept out Nigel Hasselbaink after he had evaded the attentions of Warren,
Hasselbaink then got a a second chance to open the scoring soon after, latching on to Stevie May's pass, but he could not beat Brill from a tight angle.
Just as it looked as though Saints were getting on top, Inverness threatened to make the breakthrough, Mckay getting to the ball first just six yards out after being found by Watkins, only for Mannus to race from his line and make a timely block.
Caley Thistle, however, did take the lead with their first goal in Perth since their last win here in 2011, Warren rising highest to apply the finishing touch with his head from close range in the 42nd minute after the home defence had failed to deal properly with a David Raven cross.
Chances were at a premium after the interval, although Hasselbaink was guilty of missing an open goal, heading wide from just a few yards out after Brill had parried away David Wotherspoon's shot.
Richie Foran crashed a shot into the side-netting late on as Caley Thistle closed the gap on themselves and second place Aberdeen to seven points.
ST JOHNSTONE - Mannus; Mackay, Cregg (Iwelumo, 46), Wright (Scobbie, 37), Anderson, Millar (Croft, 71), McDonald, Wotherspoon, Hasselbaink, May, Easton. Subs unused: Dunne, Miller, O'Halloran, Banks. Booked: Hasselbaink, Millar, Wotherspoon.
CALEY THISTLE - Brill; Raven, Shinnie, Warren, Meekings, Draper, Watkins (Ross, 74), Tansey, Mckay (Vincent, 78), Foran, Doran. Subs unused: Devine, Tremarco, Polworth, Pepper, Esson. Booked: Watkins, Draper.
Referee: E. Norris.
CALEY Thistle fans, let us know your thoughts on the game and we will consider them for Tuesday's Inverness Courier.