The Primeira Liga giants claimed a 1-0 win in the quarter-final first leg on Thursday thanks to Eliaquim Mangala's 31st-minute goal.
But Sevilla have good news heading into the return leg at home with Porto's Fernando, who was red-carded, and Jackson Martinez both out suspended.
Despite the absence of Martinez, who has scored 25 goals in all competitions this season, Emery said it will not disrupt their opponents.
"Regardless of their absences or ours, we consider Porto to be a great team, which comes before any individuals," Emery said.
"We believe that our team can do better than they have today, most of all in attack. It’s an adverse result, but we still have options."
Mangala headed in a Ricardo Quaresma cross for the game's only goal at the Estadio Do Dragao, giving Porto an advantage heading into the second leg.
Emery was disappointed with his side's performance, but said the tie is still there to be won by the La Liga outfit.
"When we wanted to provide more depth to our game, we didn't have any clarity and that's been our handicap, either because we weren't able or because of the strength of Porto," he said.
"The result has continuity for the second leg and in front of our own fans, we'll have more arguments to win the tie."
Emery defended star attacker Ivan Rakitic after the Croatian was unable to reproduce the strong performances he has so far this season.
"Ivan takes on a lot of responsibility, but we can't just allow him to do everything," he said.
