Cristiano Ronaldo's first Champions League hat-trick gave Real Madrid a 4-1 win at Ajax which puts Jose Mourinho's side clear on six points in Group D.
A second successive Champions League defeat for Frank de Boer's side makes it likely that Manchester City are in a straight fight with Borussia Dortmund for the second qualification spot.
Ronaldo gave Real the lead when sweeping in Karim Benzema's cross to become the eighth man to reach 40 goals in this competition. Benzema, who scored against Ajax in last year's group stage, grabbed the second just after half time with a stunning overhead kick.
Ajax pulled a goal back through Niklas Moisander but Ronaldo, who scored three times against Deportivo on Sunday, scored twice more to record back-to-back hat-tricks for the second time in his career.
Souleymane Camara's last minute goal gave Montpellier a 2-2 draw at Schalke to give Arsenal a two-point cushion at the top of Group B.
The French side went ahead before Julian Draxler, at 19 years and 13 days, became the youngest German Champions League scorer. Klaas-Jan Huntelaar's penalty looked to have given Schalke the points before Montpellier's late rally left Schalke with four points.
Porto top Group A after their 1-0 home win over Paris St-Germain.
And a late own goal by the Slovakia defender Tomas Hubocan spoiled Zenit St Petersburg's comeback and handed Milan a 3-2 win in Russia.