Christian Kum fired the visitors into an unexpected lead five minutes before the break but Moussa Dembele began the fightback with the leveller for AZ after 50 minutes.

Further strikes by Maarten Martens (63), Mounir El Hamdaoui (79) and Nick van der Velden (84) made sure of the victory for AZ, who are now 11 points clear of second-placed FC Twente with just five games remaining.

Heerenveen missed the chance to keep the pressure on third-placed Ajax as they were held to a 1-1 draw at Heracles Almelo.

Fourth-placed Heerenveen took the lead after 16 minutes when Kristian Bak Nielsen netted, but Heracles ensured a share of the spoils thanks to Mark-Jan Fledderus' 81st-minute effort.

Heracles ended the night with 10 men after Kwame Quansah was sent off in the last minute for punching Patrik Ingelsten.

PSV Eindhoven moved to within three points of Heerenveen courtesy of a 2-0 win at Sparta Rotterdam, Balazs Dzsudzsak and Ola Toivonen bagging the goals in quick succession just before the break.

A goal by Evgeniy Levchenko four minutes into injury time saw FC Groningen claim their fourth away win of the season at FC Utrecht.

The Ukrainian hit a shot from 20 yards high into the right-hand corner of the net to give the visitors a victory they barely deserved after Utrecht had dominated for large spells.

On Friday, FC Twente missed the chance to keep the pressure on AZ as they drew 1-1 at NEC Nijmegen.