Caley Thistle watched Kilmarnock clinch the Championship title – then returned to winning ways at Morton with every intention of following them into the Premiership.
Killie’s 2-1 home win against nearest challengers Arbroath gave them a title party at Rugby Park on Friday night.
The Inverness club dropped out of the top-flight in 2017 and have seen neighbours Ross County since return there three years ago after just 12 months after relegation.
A three-month winless spell between mid-December and mid-March still hurts, despite six draws during that period keeping them in the promotion play-off chase.
ICT’s 2-1 win over Killie just over a week ago made certain of a play-off position.
After losing 2-1 at now relegated Queen of the South on Tuesday, they grasped their second chance to secure third spot with a 1-0 victory over Morton at Cappielow.
A superb strike from Inverness-born midfielder Roddy MacGregor just before the half hour mark made all the difference and earned ICT their fifth win from their last seven fixtures.
That is welcome form ahead of the play-offs on May 3 and 6, which will almost certainly be against Partick Thistle, who have a three-point and eight-goal lead over fifth-placed Raith Rovers with one game remaining.
The Inverness line-up had a more familiar look, with defender Kirk Broadfoot, Roddy MacGregor and strikers Billy Mckay and Austin Samuels back in.
On-loan Dundee United attacker Logan Chalmers, with five goals in five games, was an absentee, as was defender Danny Devine and forward Shane Sutherland, with Joe Hardy dropped to the bench.
Early booking for ICT skipper Welsh
The game got off to an unusual start with Inverness captain Sean Welsh booked inside a minute for a challenge on Gavin Reilly after he casually lost possession outside the box.
From the set-piece, Cameron Blues tested Mark Ridgers, but the goalkeeper held it.
Right-back David Carson was a real driving force and his delivery was nodded just wide by Aaron Doran.
Former Aberdeen loanee Samuels should have done better when Doran lined him up in the box, but a poor early touch allowed keeper Jack Hamilton time to block him.
Morton were a threat too though and Gozie Ugwu headed wide when he connected with a whipped-in cross from Reilly.
MacGregor, who is just back from injury, then showed great vision to feed the ball out to Robbie Deas, but the left-back’s shot flew well wide.
However, the winner arrived from a Carson corner. MacGregor collected the ball and guided a terrific swerving shot beyond Hamilton into the net.
Walsh denied by goal-line clearance
Just after the break, substitute Tom Walsh had a shot cleared off the line by Iain Wilson as the visitors sought a killer second goal.
Walsh had replaced Doran early in the second half, with the midfielder perhaps picking up a knock.
Morton, still keen to end their home term with a positive result, then went close when Robbie Muirhead’s effort just dipped over Ridgers’ crossbar.
That was as close as it came for Ton, with Deas flashing a header wide for Inverness.
There was also a hearts-in-mouth moment for Morton when substitute Lewis McGrattan blazed the ball over his own crossbar when he intercepted a run from match-winner MacGregor.
Joy for ICT and Morton in the end
Time ran out for the hosts, but for Inverness there was delight at full-time, safe in the knowledge they were certain of finishing third in the second-tier.
The hardy band of Inverness fans, who were in full voice all afternoon, left in high spirits, thrilled by a swift, sharp response from their team following their midweek set-back in Dumfries.
There was some home comfort for Ton manager, former Inverness midfielder Dougie Imrie at full-time too, as results below them ensured they would remain a Championship club.
His improvement of the Greenock side since arriving in December took them away from the danger zones in reality and he’s now planning for next term.
Caley Thistle round off the regular season on Friday at home to Hamilton, where a number of key players may well be rested to allow others needing game-time to play.
HOW THEY LINED UP –
MORTON (3-4-1-2) – Hamilton 6, Ledger 6 (Hynes 59), Strapp 6, McLean 6, McEntee 6, Blues 6, Muirhead 6 (McGrattan 81), Ugwu 6, Brandon 6 (Lyon 59), Reilly 7 (Oliver 84), Wilson 6 (Easdale 81). Subs not used: Bysouth (GK), Jacobs, Russell, King.
CALEY THISTLE (4-2-3-1) – Ridgers 6, Duffy 6, Welsh 6, Deas 6, Carson 7, Mckay 6, Doran 6 (Walsh 48), MacGregor 7, Broadfoot 6, McAlear 6, Samuels 6 (Harper 66). Subs not used: Mackay (GK), Hardy, Hyde.
Referee – Alan Muir.
Attendance – 1717.
Man of the match – David Carson.