Ronald Koeman triumphed in the battle of the brothers in De Eredivisie on Sunday, as he led his PSV Eindhoven side to victory over older sibling Erwin's Feyenoord.
The game of the day witnessed reigning champions PSV prevail 2-1 at the Philips Stadion thanks to goals from Jefferson Farfan and Alex.
Diminutive Peruvian winger Farfan (8) got the ball rolling, with Brazilian international stopper Alex doubling the lead on 43 minutes.
Even though youngster Jonathan de Guzman hit back inside two minutes, PSV had too much for their rivals in the morning kick-off.
29-time league champions Ajax lost their 100 percent record in a 2-0 defeat away at Roda JC.
Henk ten Cate's side had started the season in almost perfect fashion, scoring ten and conceding one in their first three games.
However goals from Dave de Fauw (9) and Andres Oper (65) led to their downfall as they were overtaken by FC Groningen and Heerenveen as well as their opponents on Sunday as the trio joined AZ Alkmaar in the top four.
Louis van Gaal's AZ side were unable to move two points clear at the top of the table after drawing 2-2 at home to Twente Enschede.
The visitors twice took the lead through a Blaise N'Kufo penalty (14) and Sharbel Touma (81), but former Rangers forward Shota Arveladze and Moussa Dembele ensured the spoils were shared.
Heerenveen also moved onto nine points courtesy of a convincing 3-0 home win over NEC Nijmegen, with Afonso Alves (29), Lasse Nilsson (61) and Danijel Pranjic (77) getting the goals.
Groningen went second on goal difference when Stefano Seedorf struck with two minutes to go to give them a 1-0 win at Sparta Rotterdam.