Celtic faced an early onslaught from the Portuguese side and Douglas had to dive down to his left to save Maniche's 35-yard effort in the third minute.

Joos Valgaeren was soon walking a disciplinary tightrope after being booked for a foul on Deco in the eighth minute.

The game was surprisingly open considering what was at stake, but Celtic were finding it difficult to cope with the pace of the Porto frontline.

But Celtic started to settle down with Larsson and Didier Agathe causing plenty of problems themselves.

The Swede won his side a free-kick in the 21st minute after being brought down by Jorge Costa.

Larsson stepped up and unleashed a powerful low drive from just outside the area which Vitor Baia got down well to save.

A minute later and Douglas was also called into action when Deco struck a right-foot shot from 23 yards which the Scotland man comfortably saved.

Sutton was fortunate not to be booked on the half hour after a late challenge on Nuno Valente.

Moments later Agathe was also lucky not to be cautioned after he brought down Dmitri Alenichev in full flight.

Celtic’s defence was far too easily sliced open in the 33rd minute when Derlei found Deco in the box.

His shot was again saved by Douglas from a tight angle to save the blushes of Balde, who was found wanting for pace.

But the men from Glasgow responded well again and Sutton and Larsson both nearly got on the end of inviting Agathe crosses into the box.

European Cup winner Paul Lambert was in the wars in the 38th minute after taking a Deco free-kick full in the face.

More Porto pressure followed and Neil Lennon had to step in to clear the danger after Alenichev’s cross sparked a nervous goalmouth scramble.

But Douglas came to Celtic’s rescue in the 40th minute when Maniche sent Deco away and his shot was superbly deflected behind off his legs.

The goalkeeper could not do anything to prevent Porto from going ahead in the final minute of the half when Derlei fired home after Douglas had parried Maniche’s shot into his path.