Inverness went second in the SPL with a 3-2 victory at Hearts, whilst Motherwell were comprehensively beaten 3-0 at in-form Ross County.
Hearts' top-six ambitions in the Scottish Premier League took a setback as European hopefuls Inverness posted a thrilling win at Tynecastle.
The home side were undone by a Gary Warren double which came either side of Billy McKay's 22nd strike of the season.
Hearts had twice equalised through Jason Holt and a deflected Andy Webster strike - but both times handed the initiative back to their Highland visitors within minutes.
Defeat leaves Hearts in 10th place, seven points away from the top half of the league, while Inverness regained second spot with just their second win in eight games.
Ross County stretched their unbeaten run in 2013 to eight games with a 3-0 win over Motherwell.
Ivan Sproule scored his fifth goal in as many starts to give County the lead, while second-half goals from Richard Brittain and Iain Vigurs completed a fine win.
Rowan Vine's scrambled goal early in the second half consolidated St Johnstone's position in the top half of the league standings as they saw of St Mirren 1-0.
Saints are now into fourth, level on 40 points with Motherwell, who drop to third, while St Mirren are eight points adrift of the top six with six games until the split.
Aberdeen were unable to make their chances count as Kilmarnock battled back to earn a 1-1 draw at Rugby Park.
Rory Fallon's brilliant volley gave the Pittodrie side the lead before Paul Heffernan got Kilmarnock back on terms five minutes before half-time.