Francisco Sandaza's penalty secured a 1-0 win in Inverness and lifted St Johnstone into the top four of the Clydesdale Bank Premier League.
The Spaniard netted his 18th goal of the season in the 41st minute from the penalty spot - and it proved enough to stretch the visitors' unbeaten league run to six games.
Only the woodwork prevented Caley Thistle substitute Claude Gnakpa earning his team a draw in the third minute of injury time.
A far from meaningless game, the rearranged fixture from snowy January 2 gave both teams an opportunity to climb the table. St Johnstone strengthened their bid for European football next season by leapfrogging Dundee United, while Inverness missed the chance to rise above Aberdeen and St Mirren into eighth.
Caley Thistle top scorer Gregory Tade - who netted the winner at Pittodrie - was first to test keeper Alan Mannus when he connected with a long ball from Piermayr. It was a rare opportunity in an opening 15 minutes of few chances.
The visitors created their first chance midway through the half when Liam Craig headed a David Mackay cross a couple of yards wide.
Ross Tokely's header from a Greg Tansey free-kick was saved well by Mannus - and moments later Sandaza made Caley Thistle pay for their missed chances. Tade barged into Craig and referee Willie Collum wasted little time in awarding the penalty, which was despatched with aplomb by the Perth side's top scorer.
After the interval, Sandaza might have doubled the lead after a rampaging run down the right but his angled effort went inches wide, evading his onrushing strike partner Cillian Sheridan. Caley Thistle hit back with captain Richie Foran's header flying just over the bar.
Home fans were on their feet in 79 minutes thinking McKay had equalised but his low shot from 12 yards hit the stanchion behind the goal before rippling the net.
At the opposite end Tuffey produced a terrific diving save to deny Sandaza a second in the closing stages. Inverness could have snatched a last-gasp equaliser but Mannus snatched a Gnakpa cross off Foran's head before the French attacker hit the top of the bar from 15 yards seconds later.
Source: PA