Arsenal spent €40 million to acquire the Chile international from the Camp Nou club earlier this summer, with the star set to make his debut in the pre-season Emirates Cup tournament on Saturday.
Despite playing primarily as a winger for Barca, Alexis could be deployed as a striker at the Emirates and Wenger suggests he will shine in the role, without Messi beside him to sap the spotlight.
"He first came on my radar when he played at Udinese and then afterwards, when he went to Barcelona," the Frenchman told The Daily Mirror.
"He is a striker. He’s a good finisher, who made a great impression in Italy. I saw him there and he was really outstanding. It was a bit more difficult for him at Barcelona but it’s like you can see with Neymar at that club, there you have Messi.
"When you see Neymar with Brazil and Neymar with Barcelona he’s not the same. I like the fact Alexis can play left, right, up front and that’s why I went for him."
Wenger admits Arsenal struggled when Theo Walcott sustained a season-ending injury in January and so was keen to recruit a player with similar attributes and he is keen to see how the 25-year-old adapts to Premier League life.
"I love pace and when we lost Walcott we suffered a little bit, yes, on that front," he added. "So I took him because he is a player who has the qualities of Walcott, he goes behind the defenders off the ball.
"And with the quality of his runs he can be very important for us. I think he will give us an extra dimension, in terms of quality and threat. And I hope I’m right."