The former Gunners defender believes the Chilean's experience and success in the tournament with Barcelona will help the club progress this seasonAlexis Sanchez is the man to make the difference for Arsenal in the Champions League this season, says ex-Gunner Sol Campbell.
The Londoners kick off their European campaign on Tuesday as they take on Besiktas in Istanbul in the first leg of their Champions League playoff.
Arsene Wenger is desperate to make an impact on the competition after a succession of last 16 exits in recent years, but Campbell believes that new big-money signing Sanchez can take the Gunners to the next level.
"It is important to bring in players like Alexis who have played in and won the Champions League," Campbell told Goal.
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"Alexis understands the tournament. We have been there a number of times in the Champions League and it is all about every year being in the game and pushing hard.
"We just need that bit of luck to go our way but you also have to put your neck on the line and buy players – which we are now. You need to be in it to win it and that is what Arsenal are trying to do.
"They are not spending crazily everywhere but if someone comes up they are now prepared to go for it."
Sanchez arrived from Barcelona last month on the back of a successful World Cup with Chile, and Campbell is certain he will set the Emirates alight.
"Alexis is definitely going to be a good signing for Arsenal," the former defender, who had two spells at the Gunners as a player, predicted.
"He has come from a fantastic club in Barcelona so he knows the pressure of playing in that kind of environment.
"The pressure will be the same at Arsenal so that is a good thing. His dynamics are good, he knows where the goal is and is very workmanlike at getting back into position as well.
"He knows how to play in big teams and that is what you need in a player. You need big-time players who also work hard, so he has a fantastic balance."