Kevin Phillips got Birmingham's bid for a quick return to the Premier League off to a winning start as his injury-time strike sealed a 1-0 win over Sheffield United on Saturday.
Phillips came off the bench to break United's stubborn resistance seconds before full-time at St Andrews with a neat turn and finish from Garry O'Connor's flick.
It was the perfect way for the former England striker to mark his debut following a free transfer move from West Bromwich Albion.
Alex McLeish's side are favourites to win promotion from the Championship following their relegation last season, but they will have to improve on this unconvincing display.
United, who gave a debut to China midfielder Sun Jihai, frustrated them for long periods and can consider themselves unlucky not to have taken at least a point.