"We're been written off twice already I think," said Vermaelen. "We're still in the race for both things, for the league and the Champions League, but you have to stay focused on every game and the next game is Hull City. You have to win every game.
"We will see at the end of the season. You have to focus every game and we will see where we are at the end."
Arsenal's resurgence has been without Robin van Persie after the Holland forward damaged ankle ligaments in November, while against Porto they were missing the influence of skipper Cesc Fabregas.
Fabregas is rated as "50-50" by Wenger to face Hull at the KC Stadium at the weekend.
"Cesc is really important for us but we have a lot of good players in the squad who can fill in his place," Vermaelen said.
The emphatic 5-0 victory over Porto came courtesy of Nicklas Bendtner's hat-trick, three days after he missed four clear-cut chances in the victory over Burnley.
"As a striker you have to stay confident all the time because there are some games when you don't score and that was the case on Saturday," Vermaelen said. "Against Porto he responded brilliantly. He didn't only score three goals, he won a lot of headers and that is important for the team.
"He doesn't struggle with confidence and that is a good thing for a striker. You always need a good centre-forward who scores goals for the team, he did that against Porto and I hope he will score a lot of goals in the future.
"He is still young, He has a lot of qualities - he's here at Arsenal so that means he has a lot of qualities."
Bendtner is known to be assured about his own ability - even if his treble takes his tally to just eight for the season - and Vermaelen saw no difference in the striker's attitude after his last two games.
"On Saturday he was still confident and I appreciate that because for a striker you have to be like that all the time," said the Belgium international. "After Porto he was no different to how he was against Burnley, he was just happy with the three goals and how he performed."
Victory against the Portuguese champions booked a place in the last eight of the Champions League, with Vermaelen adding: "I'm convinced we can win this competition."
Andrey Arshavin, who set up three goals against Porto, does not mind who Arsenal get in the quarter-finals.
He told his official website: "Honestly, It doesn't matter for me who gets there. Therefore, I do not want to make any predictions. We should play our own football against any opponent."
Emmanuel Eboue, who scored the fourth goal against Porto, is also determined to go one better than last season when they reached the semi-finals.
"Last year and this year is not the same because this year we are more comfortable and I think if we continue to play together like against Porto then why can we not do something?" he said.
Eboue was jeered by his own fans last season but is now a cult hero and wants to end the club's five-year trophy drought.
"I never said I wanted to move," he said. "I have got two more years with Arsenal and I feel very well here. I want to win something for the club because they have helped me a lot, so I want to win something for them.
"Arsene Wenger is always with us when we have a bad day so for me I think he is like our Daddy so we are all happy to play for him."
Champions League 2009/10 Win Outright: Arsenal 8/1