Dusan Tadic scored the only goal of the game five minutes before the break as Steve McClaren's side notched up its eighth league victory of the campaign.
PSV is in hot pursuit after a 2-1 triumph at PEC Zwolle, with Joey van der Berg turning from hero to villain after he scored at both ends.
The defender gave the home side the lead after 54 minutes but the scores were level with 15 minutes left through defender Timothy Derijck and the game was won four minutes later after van der Berg put the ball in his own net.
Ajax, fresh from a mid-week victory over Manchester City, could only draw 2-2 with Feyenoord after conceding a last-gasp equaliser.
Christian Eriksen gave Ajax a 12th minute lead, but Jean Boetius levelled for Feyenoord nine minutes later.
The Amsterdam club was ahead once again three minutes into the second half through Siem de Jong, but found itself down to 10 men after 75 minutes after centre half Niklas Moisander's was red-carded.
And Ajax was made to pay as the home side snatched a point in stoppage time through Graziano Pelle.
Ninos Gouriye hit a hat-trick to lead Heracles to a 6-3 win over Heerenveen.
The visitor went in front after four minutes thanks to Filip Djuricic, but was pegged back by Gouriye after 17 minutes.
Samuel Armenteros put the home side in front before Everton extended its advantage.
Gouriye notched his second after 57 minutes, with Alfred Finnbogason scoring Heracles' second, before Gouriye completed his treble mid-way through the second half.
Finnbogason made it 5-3 10 minutes from time, but Thomas Bruns was to end the scoring in stoppage time.
Vitesse Arnhem's title aspirations took a blow as Johann Berg Gudmundsson netted an 88th-minute winner as AZ emerged with a 2-1 victory at the Gelredome.
Roy Beerens' strike six minutes before the break put the visitor one ahead at the interval before Marco van Ginkel brought his side level after 72 minutes.
However Gudmundsson was on hand in the 88th minute to give his mid-table side the win against third-placed Vitesse.