Meanwhile Chelsea's perfect record in Group F ended with a 1-0 loss at Marseille and Bayern Munich beat Basel 3-0.
Real Madrid's Benzema hits three against Auxerre
Karim Benzema has rarely upstaged Real Madrid teammate Cristiano Ronaldo but the France striker achieved that feat with a Champions League hat-trick in Wednesday's crushing 4-0 win over Auxerre.
Benzema, 22, had previously managed just three goals in all competitions this season and was behind Gonzalo Higuain in the pecking order under new coach Jose Mourinho.
The former Olympique Lyon player, in his seventh start of the campaign, took his chance with aplomb at the Bernabeu as a second-string Real brushed aside Auxerre.
Ronaldo also chipped in with a goal, his 20th of the season in 21 matches in all competitions.
Auxerre's efforts were in any case in vain as Ajax Amsterdam's 2-0 victory at AC Milan secured third position in Group G for the Dutch side and a spot in the Europa League.
The nine-times European champions Real had already won the group, with second-placed Milan also assured of a place in the last 16.
Ronaldo, one of three regular first-teamers in the suspended Mourinho's starting 11, crossed for Benzema to nod in the opening goal in the 12th minute.
The Portugal winger lashed home the second in the 49th after Marcelo's fine through ball sent him clear and Benzema netted in the 72nd with a low shot.
He then intercepted an attempted clearance by goalkeeper Olivier Sorin before lifting the ball into an empty net to complete his treble just before the end.
"I am very pleased to have scored three goals," Benzema told Spanish television. "I am feeling better every day and that is being reflected on the pitch.
"I am going to work hard to play like I have done today all the time."
Meanwhile Arsenal, AS Roma and Shakhtar Donetsk became the final three teams to reach the knock-out stage. Roma secured second place in Group E, behind Bayern Munich, by drawing 1-1 at Cluj. FC Basel came into the final matchday needing to beat Bayern to stand any chance of catching Roma but were thrashed 3-0 in Germany.
Group H had both qualifying spots open but Shakhtar finished top by winning 2-0 at home to FC Braga, and Arsenal joined the Ukrainian champions after a nervy 3-1 victory over Partizan Belgrade.
Chelsea's perfect record in Group F ended with a 1-0 loss at Marseille to increase the pressure on manager Carlo Ancelotti.
The draw for the last 16 will be held on December 17, with group winners and teams from the same country prevented from playing each other.
Roma only needed a point to go through, but looked as if they would pick up all three when Marco Borriello put the Italian side in the lead in the 21st minute from 12 yards.
Lacina Traore headed home in the 88th to earn the Romanian team a draw. France winger Franck Ribery scored in both halves for Bayern, who were already assured of winning the group. Defensive midfielder Anatoliy Tymoshchuk also found the target for last season's runners-up.
Basel finished third and will play in the Europa League. Arsenal reached the second round of the Champions League for the 11th straight year but were given a scare by Partizan and needed late goals by Theo Walcott and Samir Nasri to seal the win. Robin van Persie, making his first start in the competition in more than a year, put the Gunners ahead from the penalty spot in the 30th after he was fouled by Marko Jovanovic.
But Arsene Wenger's side, which climbed to the top of the Premier League last weekend, were far from their best and conceded when Cordova Cleo's shot deflected off Sebastien Squillaci and over diving Arsenal goalkeeper Lukasz Fabianski in the 42nd minute.