The Blancos, taking 16 of 18 possible points, cruised to a first-place finish in Group B. The Danish side, with a meager four points, is out of European play for this season. (Agencies)
Luka Modric opened the scoring for the visitors with a strike in the 25th minute and Ronaldo made it 2-0 just three minutes into the second half.
The Portuguese international chalked up nine goals in the six matches of the group stage, a new record in the two-decade old competition featuring Europe's elite clubs.
The identity of the second Group B squad to advance to the round of 16 won't be decided until Wednesday, when Juventus, at six points, and Galatasaray, with four, are scheduled to resume play in Istanbul after Tuesday's contest was suspended due to heavy snow.
Play was stopped at the 30-minute mark with the teams tied 0-0.
In Tuesday's other action, Bayer Leverkusen beat hapless Real Sociedad 1-0 to grab the second playoff berth from Group A over Shakhtar Donetsk, who lost 1-0 to group winner Manchester United.
Benfica edged Group C winner Paris Saint-Germain 2-1 to boost their point total to 10, the same as Olympiacos.
But the Greek side, victorious 3-1 over Anderlecht Tuesday, snagged second place on the strength of having defeated the Portuguese squad in head-to-head play.
Defending champion Bayern Munich retained the top spot in Group D despite losing 3-2 at home Tuesday to Manchester City.
While each team finished with 15 points, the German club took first place on goal differential.
The Blancos, taking 16 of 18 possible points, cruised to a first-place finish in Group B. The Danish side, with a meager four points, is out of European play for this season.