El Hamdaoui double not enough for Ajax
Mounir El Hamdaoui scored twice on his league debut for Ajax but Martin Jol's side let a 2-0 lead slip to draw 2-2 with FC Groningen on their opening game of the Eredivisie season.
El Hamdaoui joined Ajax from AZ Alkmaar and made a quick impression for the Amsterdam club, scoring after 50 and 61 minutes.
However, Groningen responded superbly with Tim Matavz (72) and Nicklas Pedersen (86) giving the home side an unlikely point.
Three second half goals enabled Feyenoord to come from behind and make sure of a 3-1 victory in their Eredivisie opener against FC Utrecht.
Ricky Van Wolfswinkel gave the visitors a 12th-minute lead but Alje Schut's own goal seven minutes after the restart lifted the home side and they picked up all three points courtesy of further goals from Luigi Bruins and Leroy Fer.
Matthew Amoah's late strike rescued a point for NAC Breda in their opening Eredivisie match at home to AZ Alkmaar.
AZ took the lead through Erik Falkenburg after 58 minutes but failed to close out the match as Amoah popped up with the leveller 11 minutes from time.
Two second-half penalties from Lasse Nilsson helped Vitesse Arnhem come from behind to open their Eredivisie campaign with a 3-1 victory over ADO Den Haag.
Lex Immers gave the visitors the lead on the quarter-hour mark, but in first-half stoppage time Wiljan Pluim forced the ball home to bring Vitesse level. And Nilsson then showed a cool head from 12 yards with two spot-kicks in the 57th and 71st minutes.