Cristiano Ronaldo's second hat-trick in four days allowed Real Madrid to take charge of the Champions League's toughest group yesterday.
Arsenal, FC Porto and Malaga joined the Spanish power in earning second straight wins in the competition.
Ronaldo's three-goal performance upstaged a spectacular overhead kick by Karim Benzema in Madrid's 4-1 win against Ajax, giving Jose Mourinho's team a maximum six points in Group D.
Manchester City's struggles in Europe's top club competition continued, though, after being outclassed by Borussia Dortmund in the same group. The English champions escaped with a 1-1 draw, thanks to Mario Balotelli's 90th-minute penalty kick.
AC Milan kick-started their campaign by inflicting a rare home loss on Zenit St Petersburg, with an own goal by Tomas Hubocan sealing a 3-2 win for the seven-time European champions. They have four points in Group C, two behind Malaga after the Spanish side beat Anderlecht 3-0 to be one of seven teams with a perfect mark after two group games.
Arsenal beat Olympiakos 3-1 and Porto overcame Paris Saint-Germain 1-0 to also maintain spotless records.
Ronaldo's first hat-trick in the Champions League came after he also scored three against Deportivo La Coruna in the Spanish league on Sunday. He has 12 goals in 10 games in all competitions this season. With 42 goals, he is the eighth player to score more than 40 goals in the Champions League.
While Ronaldo's low curler from the edge of the area and a clever chip were impressive goals, they couldn't compete with the stunning acrobatic effort from Benzema off Ronaldo's right-wing cross.
Madrid already look safe to go through to the knockout stage, and on current evidence, Dortmund looks the most likely to join Real.
The German champions outplayed City with an attacking display but came up against a goalkeeper in Joe Hart who may have played the best game of his career. Hart denied Dortmund with a string of fine saves until Marco Reus finally put the visitors ahead in the 61st minute. However, Balotelli rescued a point for City.