Derk Boerrigter and Lasse Schone had goals on each side of halftime as Ajax defeated Groningen, 2-0, on Saturday at Amsterdam ArenA for its fifth straight Eredivisie win.
Ajax totaled just 18 points through its first 11 games, but with a maximum 15 over its last five, has climbed to fourth in the table and within one point of the summit with the top three sides yet to play Sunday.
Groningen had a five-game unbeaten streak snapped as it slipped into the lower half of the standings in 11th place.
RKC Waalwijk vaulted into the upper half as Cuco Martina and Florian Jozefzoon scored in a 2-0 win Saturday over NEC.
Jens Toornstra scored in the second half as Den Haag tied Zwolle, 1-1, and AZ Alkmaar saw its winless run reach five matches after a 0-0 draw against Willem II.