Saliba impressed on his Premier League debut against Crystal Palace earlier this month, but endured a more difficult test at the Emirates on Saturday.
Arsenal ran out 4-2 winners in north London, with the French defender responsible for one of those Leicester goals after inadvertently heading the ball past Aaron Ramsdale and into his own net.
Xhaka is convinced that such a setback will not knock Saliba’s confidence as he has been impressed by his maturity since joining the first-team squad this summer.
“This is football,” said Xhaka. “People only see the own goal but maybe, hopefully, they’ll see what a game he had. This guy is 21. I think in his first game in the Premier League for Arsenal he was unbelievable.
“You can see how…he looks like he is 30. He has discipline and big character. He is not so loud, but he is a proper leader in my eyes.
“You can see he is amazing. He has a lot of quality and yeah, we forget the own goal because for 90 minutes he had a great, great game.”
Arsenal have made a perfect start to the new season, winning both of their opening games in the Premier League. New striker Gabriel Jesus caught the eye in the win over Leicester, scoring twice and providing two assists.
The Brazilian has transformed the way Arsenal attack and become a key part of the leadership group in the dressing room, too.
Xhaka has hailed his impact and is convinced that the striker will only get better as he continues to settle following a £45million move from Manchester City.
Asked if Jesus was the missing piece of the puzzle under Mikel Arteta, Xhaka said: “It looks like it at the moment.
“He is so important for us. You can see how much he works, not only because he is scoring and giving assists, but he works for the team unbelievably.
“He is like this every day in training. When he doesn’t score, he’s hungry and this is a striker who makes a difference in the end in the box, and we are so happy to have him. Let him continue and reach these numbers more and more.”