Alfred Finnbogason continued his prolific form this season with a second-half penalty as Heerenveen closed on fourth-placed Feyenoord with a 3-0 home win over ADO Den Haag.
Kenny Otigba broke the deadlock in the 58th minute and then Iceland international Finnbogason made it 2-0 from the spot with his 20th Eredivisie goal of the season, leaving him clear at the top of the scoring charts.
Substitute Rajiv van la Parra then added a third goal late on to seal the victory as Heerenveen moved to within four points of Feyenoord, who drew with Vitesse Arnhem on Friday night.
Two goals in the opening 17 minutes from Nemanja Gudelj earned AZ Alkmaar a 2-0 home win over FC Groningen and sixth spot in the table, while PEC Zwolle remain two points further back after beating Roda JC 3-1.
Zwolle saw Ryan Thomas's 19th-minute opener cancelled out by Mitchell Donald just after the hour, but the home side were not to be denied and two goals in the final 13 minutes from Guyon Fernandez (penalty) and Fred Benson sealed the triumph.
Saturday's other match saw NAC Breda win 2-1 at mid-table rivals Heracles, Jordy Buijs (38) and Rydell Poepon (61) putting the visitors in charge before Bryan Linssen (71) pulled a goal back for the hosts.