Bielsa’s men slipped back to third and one point behind Sheffield United, who won 1-0 at Preston as Leeds lost by the same score to Garry Monk’s Blues, who became the only side this season to record the double over the Whites.
As was the case in September, Che Adams proved the difference with the Birmingham forward following his Elland Road double with another strike to sink the Whites in the 29th minute.
Bielsa took responsibility for the Blues loss in the autumn, taking off Kalvin Phillips after 34 minutes and insisting he should have lined up with a back three to counter the threat of Birmingham’s front two.
Seven months on and Bielsa went with a back three from the start at St Andrews with Mateusz Klich playing in a deep-lying midfield role.
The plan failed to work, albeit Leeds squandered some glorious chances, and Bielsa was again prepared to take the blame, lamenting his substitutions.
Bielsa waited until the 70th minute to send on top-scorer Kemar Roofe, who returned from injury to take the place of misfiring striker Patrick Bamford with winger Jack Clarke replacing Klich at the same time.
Stuart Dallas had been brought on at half-time for Jack Harrison.
“The position of Klich didn’t help the team to create chances in attack,” said Bielsa. “After they scored we moved his position and he started to attack more. Our attacking improved.
“The decisions I made from the bench couldn’t change the result in the way I wanted to do. The changes I made weren’t enough so I would criticise myself for that. In the last 20 minutes we couldn’t create chances. We had a lot of options on the bench to make changes and the decisions on the changes were not the best ones. I take the responsibility about the positioning of Klich, too.”
Leeds wasted a fine chance in the third minute when Tyler Roberts blazed wide. Then Bamford could only prod a close-range effort against a post and Birmingham struck 60 seconds later when Adams fired into the bottom left corner.
Bamford also blazed over from six yards after the break and the striker had a header kept out by a fine save from Lee Camp.
Yet it was Birmingham who offered seven attempts on goal to United’s one with Kiko Casilla pulling off several good saves to deny Adams, in particular, a second.
Birmingham City: Camp, Colin, Morrison, Dean, Pedersen, G Gardner (Davis 45), Kieftenbeld (Harding 57), Maghoma, Mahoney (Jota 76), Adams, Jutkiewicz. Unused substitutes: Trueman, Mrabti, C Gardner, Vassell.
Leeds United: Casilla, Alioski, Cooper, Jansson, Ayling, Phillips, Klich (Clarke 70), Roberts, Harrison (Dallas 45), Hernandez, Bamford (Roofe 70). Unused substitutes: Peacock-Farrell, Shackleton, Berardi, Forshaw.
Referee: M Dean (Wirral).