The striker, who was banned for violent conduct for grappling with Arsenal's Laurent Koscielny, said on espnfc.co.uk: "To come out of this we need to be all together, and for everyone to give a little more. We are not playing well, this is not a good moment, but we have players to get out of this easily."

Costa completes his ban in Saturday's EPL clash with Southampton, but it is difficult to know who will replace him as fellow strikers Loic Remy and Radamel Falcao were not selected to travel to Portugal.

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Oscar also did not fly, while Eden Hazard and Nemanja Matic joined captain John Terry on the substitutes' bench.

Nevertheless, Costa felt Chelsea did enough to win at Porto, only to concede a "ridiculous" winner from a corner. "We had the game under control," Costa added.

"We knew it was going to be a physical game. We began well. Things changed when they scored, but we quickly equalised. In the second half the same thing happened — we were lacking concentration at key moments of the game."