Doyle finger-tipped a powerful drive from Wolves winger Matt Jarvis on to the post and then reacted quickly to keep out Steven Fletcher's close range follow-up header.
Blues boss Hughton said: "It was a brilliant save at the end. It kept us in the tie.
"That is the thing with keepers. They cannot be too troubled for most of the game which was the case.
"But we certainly needed Colin at that moment and it earned us a replay."