Manchester United are in pole position to reach the last eight after sealing a 3-2 success at the San Siro on Tuesday night, courtesy of Wayne Rooney's second-half double.
Premier League leaders Chelsea face Serie A front-runners Inter Milan next week, with former Stamford Bridge supremo Jose Mourinho coming face-to-face with the side he guided to consecutive Premier League titles in 2005 and 2006.
Arsenal's task has been made more difficult following a succession of injuries to key players, with Manuel Almunia, William Gallas, Kieran Gibbs, Alex Song, Andrei Arshavin, Eduardo and Robin van Persie all ruled out.
However, Wenger believes that his depleted side can see off Porto, and expects to be joined in the next phase by both of Arsenal's Premier League title rivals.
"I expect the three English teams to go through, yes, but I'm not a fool. I know that it will be difficult for all the three teams," he told his club's official website.
"Maybe Manchester United have a small advantage over Milan, but in the other two games it will be very tight."
"It is normal that people become a little bit complacent," he said.
"You [the media] are so used to going through. If it is not Arsenal it's Chelsea, you don't care because you travel anyway.
"But I mean you are used to having the teams in the latter stages, so you can be demanding.
"I don't have a problem with that. But, if you look across Europe, the other teams invest as well. More sometimes. So it's not guaranteed that you have success."
