Benzema hat-trick inspires Madrid
Benzema, who has struggled since joining Madrid in the summer of 2009, netted in the 11th, 72nd and 88th minutes while in-form Cristiano Ronaldo was also on the scoresheet at the Bernabeu.
The result means Madrid finish the group stages with 16 points out of a possible 18, but for Auxerre it is the end of the road after they lost out to Ajax in the race for third place and a Europa League berth.