The signing from Barcelona may have to play on the right flank because of the injury to the England international, who has yet to recover after rupturing his ACL.
Walcott ruptured his anterior cruciate ligament in an FA Cup clash with Tottenham at the turn of the year but returned to training earlier this week as the Gunners stepped up their preparations for the new season.
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However, Wenger says Walcott is still injured and claims he may have to play his new 40 million euro signing from Barcelona on the right flank instead of through the middle at the start of the season to compensate.
“He can play through the middle, he can play on both flanks and he has the qualities that I think are needed in England,” he told Arsenal's official website. “He's brave, works hard and all these qualities together made me go for him.
“At the moment he might play on the flank because Walcott is injured. As well [he can play] through the middle in some games; we can play with Giroud, we can play without Giroud in a 4-4-2 or in a 4-3-3.
“That's why he is a major signing for us [and] that's why we spend a lot of money on him. He has the quality to be efficient everywhere he plays.”
Wenger also feels Sanchez's natural desire to improve will stand him in good stead once the 2014-15 season kicks off.
“We have seen at the World Cup the South American teams have shown a great passion, great desire and true love for the game,” he added. “That is a very important quality in the success of a player.
“Our society maybe doesn't give a natural toughness anymore as much as South American society does and it's always an asset in your life when you have to work hard to get where you are. It means at least you are capable of finding the resources to do it.”