Bas Dost struck twice as high-flying Heerenveen claimed a deserved win over a FC Groningen side whose hopes of a top-eight finish continue to dwindle by the week.
Dost opened the scoring in the 24th minute and then restored his side's advantage just before half-time after Dusan Tadic had drawn the home side level.
Viktor Elm then added a third goal late on for Heerenveen, who remain within a point of second-placed FC Twente after recording their third win in four games.
Freefalling Groningen, meanwhile, are still two points behind eighth-placed Roda JC after suffering an eighth league defeat in 10 games.
Heerenveen took the lead with their first real chance of the game as Dost got on the end of Luciano Narsingh's cross to finish right-footed from five yards out.
The visitors almost made it two goals in two minutes as Narsingh tried his luck from the edge of the box, but his shot went over.
The next good chance fell to Groningen and they made the most of it to equalise in the 37th minute when Tadic headed home from close range following a cross from Tom Hiariej.
However, Groningen were level for barely five minutes before Heerenveen restored their lead, and this time there was no way back for the hosts.
Narsingh and Dost again combined, with the latter providing a fine headed finish to his team-mate's cross to double his tally for the match.
Chances were few and far between in the second half as both sides struggled to retain possession, but Heerenveen launched a rare attack in the 85th minute to make certain of the points with a third goal.
Filip Djuricic fed Elm on the left of the box and he drove a low shot past Luciano to complete the scoring.