Watford preserved their unbeaten start in the Championship with a hard-fought draw against Birmingham at St Andrew's.
Vakoun Bayo redirected Craig Cathcart's header against the inside of the post on his debut as the Hornets made a fast start.
Yet 18-year-old George Hall put Blues ahead against the run of play, arriving late in the box to meet Scott Hogan's pull-back with a smart first-time finish into the bottom corner.
Ken Sema smashed an angled drive past John Ruddy after the break to bring the Hornets level and make it two wins and two draws for new boss Rob Edwards.