Champions Celtic drew 1-1 with Ross County on Sunday to put a dent in the Victoria Park outfit's European hopes, on an afternoon that saw Dundee relegated while Kilmarnock's clash with Hibernian was abandoned.
Following victories for Inverness and St Johnstone on Saturday, County needed to win to move back within two points of a Europa League spot with two games remaining.
A brilliant finish from Iain Vigurs ensured they took points off Celtic for the third time this season but the hosts were also helped by a controversial offside decision.
Vigurs found the top corner from 20 yards following a set-piece four minutes before half-time to cancel out Anthony Stokes' early opener. But Celtic should have gone into the break with a deserved lead after Tony Watt was denied a goal by a dubious offside decision.
The draw means County are now four points adrift of third-placed Inverness, and Caley Thistle will put them out of the running for a Europa League spot before the final-day Highland derby if they beat Dundee United at home on Saturday.
Dundee's unlikely bid to avoid relegation came to end after they could only draw 1-1 with Aberdeen on home soil. St Mirren's defeat on Saturday meant Dundee could have closed to within five points with victory, but a draw leaves them seven adrift with only two games to play.
A win looked on the cards when Jim McAlister opened the scoring in the 20th minute, finding the top corner from just outside the area. Aberdeen then went down to ten men in the second period when Rory Fallon saw red for violent conduct.
However, they restored parity in the 70th minute when Niall McGinn converted a disputed penalty, and Dundee could not find a response.
The day's other game between Hibernian and Kilmarnock at Rugby Park was abandoned during the second half after a spectator had to be taken to hospital following a suspected heart attack. The score was 1-1 at the time.