Arsenal captain Cesc Fabregas insists all is not lost after their Champions League first-leg defeat at Porto.
The Gunners will have to overcome a 2-1 deficit in the return-leg at the Emirates.
"It is going to be hard for us in the second leg, but I am still confident we will prevail in the end," the Spain midfielder said.
"We will just have to see who is strongest on the night."
Fabregas added: "We knew Porto had a very quick and talented team, but the truth is we allowed them to score two very easy goals.
"You just can't let that happen at this level. Now we are 2-1 down and we are going to have to fight our way back."