The holders, who also won the Confederations Cup in Russia last year, crashed out after a 2-0 loss to South Korea on Wednesday left them bottom of Group F.
The result is the biggest surprise of an intriguing finals to date, in which favourites including Brazil, Spain and France have struggled for top form, while 2014 finalists Argentina only scraped through thanks to a last-gasp win over Nigeria.
"The level of this tournament is very balanced," he told Omnisport. "Anyone can be a surprise. It's like the Premier League: you kind of expect every kind of result everywhere.
"We should be happy we're going through. Argentina took a risk and qualified in the last five minutes, so really, in this World Cup, anything can happen."
"Surprise, surprise!" the former Borussia Monchengladbach man said. "That's football. You can see, if you're not ready to play and to fight, 100 per cent, it's difficult."
Vladimir Petkovic's side, who progressed in second place from Group E behind Brazil, will face Sweden in the next round after they topped the pool containing Germany with a 3-0 defeat of Mexico.
Xhaka is wary of taking Sweden lightly given their performances in Russia and the fact they beat Italy in a qualification play-off tie back in November.
"It's a difficult game," he said. "If you see their qualification they beat Italy over 180 minutes, they've come into the next round with Germany in the group. It's not going to be easy, but we think we can do something."
Behrami, meanwhile, hopes Switzerland can now spring a few shocks of their own as they look to challenge for the quarter-finals and beyond.
"It's going to be the two best teams in the final but maybe there is one surprise in there," he added. "Maybe we can be this surprise. Anything is possible in this World Cup."