Defender Miguel Layun has admitted Porto will have to show courage in their do-or-die Champions League clash with Chelsea after going down to Dynamo Kiev on Tuesday.
Porto will head to Stamford Bridge on matchday six of the pool phase next month sitting level on points with Chelsea in Group G, two points ahead of third-placed Kiev, who triumphed 2-0 away from home.
Andriy Yarmolenko and Derlis Gonzalez were on target as Kiev kept their qualification hopes alive.
And Layun has urged Porto, who were playing the second of seven games in a marathon 23-day span, to bounce back in London on December 9.
"It will be a difficult game in London [against Chelsea] where it will be all or nothing," he said.
"We will have to show the courage we have already shown on other occasions and we cannot let this defeat affect us.
"Tonight we just could not score goals in important moments, we were not able to take the most of the opportunities.
"We can only think of how we can improve in the next match."
Porto went into Tuesday's match needing only a point to advance to the last 16.
However, the Portuguese giants came unstuck at Estadio do Dragao after Yarmolenko converted a first-half penalty and Gonzalez sealed the points just past the hour-mark.
"Dynamo were better than us tonight. We started well, but we lost all calm after the penalty," said coach Julen Lopetegui.
"In the second half we should have played more with our heads, not with our hearts, so we were not able to surpass an opponent that, in the end, was a deserved winner."