A Richard Brittain penalty just after the hour mark was enough to secure Ross County's future in the top flight as they beat Hibernian 1-0.
In an engrossing match which produced chances at both ends throughout it was the County skipper who kept his nerve to slot away the spot-kick award after Jordan Slew was upended in the box by Scott Robertson.
Hibs must now secure their future in their final match of the Scottish Premiership season against fellow strugglers Kilmarnock on Saturday - and they could find themselves in second-bottom place beforehand if results go against them on Wednesday night.
Scott Vernon broke his 2014 goalscoring duck with a hat-trick that leaves Aberdeen clear favourites to clinch second place in the Scottish Premiership.
Vernon grabbed an opportunity presented by Adam Rooney's ankle injury to send the Dons four points above Motherwell thanks to a 3-1 victory over a much-changed Dundee United at Tannadice.
The striker netted his first goal since December when he slotted home from 10 yards in the seventh minute but United hit back when defender Sean Dillon netted with a powerful deflected strike.
Aberdeen goalkeeper Jamie Langfield made brilliant saves from Andy Robertson and Mark Wilson before Vernon nodded home 10 minutes into the second half after goalkeeper Marc McCallum had lost Barry Robson's corner. United pressed again but a mistake by Gavin Gunning allowed Vernon to complete his treble with 15 minutes left.
The result assures Motherwell of a Europa League place with United now needing to beat St Johnstone in the William Hill Scottish Cup final to qualify.
However, with the Dons 14 goals better off than Motherwell, it leaves Stuart McCall's side needing to beat Inverness at Fir Park on Wednesday and Aberdeen at Pittodrie on Sunday to finish second.