England are ranked 20th in the latest world rankings after a group stage exit at this summer's World Cup, while Switzerland are rated ninth.
"I like to be the favourite in a game, but confirmation always comes on the pitch," Petkovic told reporters.
"There's still a lot of respect for England -- no fear, but lots of respect. The Swiss FA during the past 10 years have been doing very well and improved on all levels.
"It's been a good quality improvement. Now we can say we're level with the English team."
England were criticised for a tepid performance in Wednesday's 1-0 friendly win over Norway.