Correct. One goal ahead of Arsenal does not guarantee that Porto is safe, of course this second leg match will be the biggest test for Porto to defend their back line so as not to concede because of course Arsenal will appear to attack from the start.
Moreover, Arsenal is currently on a trend of 4 consecutive wins at home, all of which occurred in the domestic league. From these 4 wins, Arsenal managed to score 14 goals and only conceded 3 goals. So overall this season Arsenal have played 18 home games. Arsenal achieved 14 wins, 2 draws and 2 defeats.
Fc Porto defense is as solid as rock but I still have believe in Arsenal to make a turn around in today's match. The good thing here is that Arsenal is playing at their home ground and we all know how strong every team is while playing at their regular play ground. The cheers from the fans and conversant ground will definitely have impacts on their performance. Bayern Munich did it last week and Arsenal can do it too, they already did in the group stage and this is the right time to repeat the history. Arsenal recent performance is really commendable, being eliminated in the UCL now will be very bad experience as they currently occupied the top spot of the domestic league table.