Rasmus Bengtsson opened the scoring in the 17th minute and then two goals in quick succession midway through the second half wrapped up the win, Kyle Ebecilio doubling the lead in the 72nd minute and Dusan Tadic adding a third from the penalty spot three minutes later.
Also on 12 points are Heerenveen, who were held to a 3-3 draw at Roda in a match which produced six different scorers and saw no side leading for more than seven minutes at any stage.
Magnus Wolff Eikrem (26 minutes), Alfred Finnbogason (62) and Joey van den Berg (67) were on the scoresheet for Heerenveen with Mitchell Donald (33), Krisztian Nemeth (60) and Guus Hupperts (70) replying for Roda.
FC Groningen had to wait until the final 22 minutes to make their numerical advantage count against 10-man RKC Waalwijk but finally managed to see off their battling visitors in a 4-1 win.
RKC lost Sander Duits to a 37th-minute red card but they managed to hold on until the 68th minute before Groningen managed to take the lead through Nick van der Velden.
Groningen quickly added a second through Genero Zeefuik but RKC refused to concede defeat and they pulled a goal back through Aurelien Joachim in the 73rd minute to set up a tense finale for the home side.
RKC could not find an equaliser though and Groningen made sure of the points with stoppage-time strikes from Krisztian Adorjan and Michael De Leeuw.
Saturday's other game saw ADO Den Haag play out a 1-1 draw at home to NEC in the battle between the bottom two sides in the division, the hosts seeing their 56th-minute lead from Mathias Gehrt cancelled out by Christoph Hemlein's 74th-minute equaliser.