UPDATE 1-Soccer-Ajax beat arch-rivals Feyenoord but PSV stay top

(updates with further result) AMSTERDAM, Sept 21 (Reuters) - Ricardo van Rhijn scored an early goal to hand champions Ajax Amsterdam a 1-0 away victory over arch-rivals Feyenoord on Sunday but four goals from PSV ensured they remained the front runners in the Dutch league. Fullback Van Rhijn hit home a fifth minute free kick from some 20 metres out as Ajax survived a furious onslaught from their hosts that saw Feyenoord hit the woodwork three times inside the opening 11 minutes. English-born Colin Kazim-Richards missed a dream chance for a goal in his first start for Feyenoord on the stroke of half-time and Ajax had goalkeeper Jasper Cillessen to thank after the break for keeping their precarious lead intact. The win moved Ajax second in the standings on 12 points, three behind PSV who beat SC Cambuur 4-0 at home. PSV punished mistakes by their previously unbeaten opponents, who were in surprise third place before the start of Sunday's matches, and had their task made even easier when Lucas Bijker got sent off for a second caution before half-time. By that stage PSV were 2-0 up with goals from Luuk de Jong and Jetro Willems and added two more in the last 12 minutes from Jeffrey Bruma and Adam Maher. PEC Zwolle stayed on 12 points after losing 1-0 to a late Markus Henriksen goal at AZ Alkmaar. Marco van Basten, who stood down as coach and then had his designated successor Alex Pastoor depart two days later, was back on the AZ bench as assistant to Dennis Haar for the win. Heracles Almelo remain rooted to the bottom of the standings without any points despite taking the lead at home to Twente Enschede, who came back to win 4-1 with Luc Castaignos scoring twice. Ruud Boymans came on for his Utrecht debut to score the only goal of their home win over Groningen, who saw their penalty just eight minutes later saved. (Reporting by Mark Gleeson; Editing by Alan Baldwin and Pritha Sarkar)