Myhill has stepped in for Foster while the England keeper recovers from a foot injury.
"He's been really good," Foster told the Birmingham Mail of Myhill. "I've said it before but I knew he'd be fine.
"I get to see him day in, day out, in training so it's no surprise to me.
"He's an international goalkeeper and you've got no worries with him. You know he'll come in and do the job.
"He's fantastic and we've needed him as well."
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