PSV Eindhoven sent a warning sign to the rest of the Eredivisie that they are serious about winning a 22nd title as they beat Excelsior 6-1.
While their opponents may be the early-season fall guys, PSV were still impressive from start to finish, with Dries Merten and Ola Toivonen sharing five goals between them.
The former scored a hat-trick, with Jeremain Lens netting the other, although remarkably the Rotterdam side had been level at one stage thanks to Mitchell te Vrede.
AZ Alkmaar maintained their fine goalscoring form with a 3-0 win at FC Groningen.
Having hammered NEC Nijmegen 4-0 in their last league outing, Gertjan Verbeek's men carried on where they had left off with Nick Viergiver scoring in the opening minute at the Euroborg Stadion.
Johann Berg Gudmundsson and Rasmus Elm added further goals in the second half to move AZ level with PSV - three points behind early leaders FC Twente.
Heerenveen clung on with nine men to frustrate Feyenoord and leave De Kuip with a 2-2 draw.
Ramon Zomer and Doke Schmidt were sent off in the final half an hour, but Feyenoord could not find a way through to snatch a winning goal. Heerenveen led the match twice but on both occasions were swiftly pegged back by the home side, who remain unbeaten with two wins and two draws from their opening four games.
The visitors' goals came from a Bas Dost penalty and another from Oussama Assaidi, with Feyenoord replying through Leroy Fer and Jerson Cabral.
In Sunday's other game, ADO Den Haag secured their first win of the season in style with a 3-0 success at ten-man De Graafschap.
ADO were 1-0 up through Aleksandar Radosavljevic's effort on the stroke of half-time when Purrel Frankel saw red with 13 minutes remaining. The visitors took full advantage, with goals from Wesley Verhoek (83) and Mike van Duinen (87) sealing the points.