Mario Mandzukic's hat-trick has ensured that Atletico Madrid will reach the last 16 of the Champions League after comfortably beating Olympiacos at the Vicente Calderon.

The Spanish champions got on the front foot from the start as Raul Garcia almost turned Juanfran's cross beyond Roberto Jimenez Gago inside the opening three minutes.

By the ninth minute, Atleti took the lead when the Olympiacos strangely passed the ball to Juanfran with the right-back finding Garcia, who beat the hapless shot-stopper.

Diego Simeone's side almost added a second when both Jose Gimenez and Koke had chances to score, but failed to hit the target.

Just after the half-hour mark, Garcia almost added got his second of the night when he received a pass from Cristian Ansaldi and his shot was inches away from creeping inside Jimenez Gago's post.

Atletico wouldn't be denied and they doubled their lead just before the break when Mandzukic netted his third goal of this season's competition from close range.

The Croatian forward almost got his fourth of the campaign in the early stages of the second half when his shot from Koke's cross was saved.

Mandzukic did add to his tally on 62 minutes when he headed home from Arda Turan's pinpoint delivery.

Moments later, the former Bayern Munich frontman completed his hat trick with another header from Gabi's accurate set piece.

Atleti almost added a fifth late on. with substitute Antoine Griezmann heading Juanfran cross just over the bar.

The French international had the ball in the net in the dying minutes, but his effort was ruled out for offside.

The Spanish champions are assured of a place in the second phase, but Olympiacos must rely on beating Malmo and hoping that Juventus are beaten by Atleti in the final round of group games in a fortnight.