Porto coach Jesualdo Ferreira fears Arsenal's greater experience could prove telling in tonight's Champions League clash.
The Group G rivals last met two years ago when Arsene Wenger's team emerged convincing 2-0 winners at the Emirates Stadium.
Porto's squad was overhauled during the summer, losing key players such as Jose Bosingwa and Ricardo Quaresma, and Ferreira believes Arsenal have a clear edge.
"There have been many changes since 2006. Arsenal have big players still but only Thierry Henry is missing who was there then,'' he said.
"Most of their players are bigger, older, better and more experienced. Porto weren't able to keep up with Arsenal in that game but we were able to qualify from the group.
"Now we have different players, some left and some have come. At the moment the only thing we can say is that Arsenal have more experience and that could affect the outcome.''
Porto have yet to win on English soil in 10 attempts and face an Arsenal team desperate to atone for their embarrassing 2-1 defeat by Hull in the Barclays Premier League on Saturday.
But Ferreira refuses to buy into talk of his Portuguese champions facing a Gunners backlash.
"I don't believe the Hull game will be of influence. These are two completely separate matches,'' he added.
"In the Champions League teams always play differently. Arsenal use different tactics to the ones they use in the Premiership.
"Arsenal losing on the weekend will not have an effect on tomorrow night.
"If Arsenal conceded a goal from the set-piece against Hull it doesn't mean anything, it doesn't suddenly become something we look at. As we all know our history in England is not that positive and we have never won here.
"It's a challenge for us and it will be difficult tomorrow. But we are a team that wants to win and our objective tomorrow is to win.
"The second game of the Champions League is a very important match in the group.''