AMSTERDAM, Jan 23 (Reuters) - Leaders PSV Eindhoven and closest rivals Ajax Amsterdam earned home wins over Sparta Rotterdam and Utrecht respectively on Wednesday to remain three points apart at the top of the Dutch league.PSV opened the scoring after 24 minutes when Danko Lazovic was set up by Balazs Dzsudzsak and Jan Kromkamp doubled their lead 11 minutes after the break. Darryl Roberts pulled one back for Sparta in the final minute before Jason Culina made it 3-1 with a long drive. Ajax struggled to break down a defiant Utrecht side but scored midway through the second half through a fine volley by Klaas Jan Huntelaar. Johnny Heitinga added a second in the 77th minute after Utrecht were reduced to 10 men following a straight red card for Sander Keller in the 71st. PSV stay three points clear of Ajax at the top with 43 points from 20 matches. Groningen thrashed 10-man NEC Nijmegen 5-1 to move into provisional third place with 39 points after 21 games, while Heerenveen also won at home by the same score against VVV Venlo and climbed to fourth with 37 points from 21. Mark Jan Fledderus struck twice in three minutes to give Groningen a comfortable halftime lead but soon after the break Jhon van Beukering pulled one back. Midway through the second half Nijmegen's Peter Wisgerhof was dismissed for a second booking and Groningen took advantage with Marcus Berg, Goran Lovre and Tom Hiariej completing a rout. Heerenveen sealed their win in the first half with Michael Bradley, Miralem Sulejmani and Jakob Poulsen on target. Gerald Sibon added a fourth on the hour while Sandro Calabro got a consolation goal for the visitors before Danijel Pranjic wrapped up the scoring for Heerenveen. Feyenoord and Twente Enschede, who have 36 points from 19 and 20 games resepctively, slipped to fifth and sixth before they meet in Rotterdam on Thursday.