Match ends, Barnsley 0, Birmingham City 1.
Scott Hogan scored the winner as Birmingham saw off struggling Barnsley at Oakwell.
Hogan's goal was his third in three games since joining the club on loan from West Midlands rivals Aston Villa.
The striker fired a fine left-footed effort past Brad Collins after being found in the box by Jude Bellingham in the 76th minute.
Barnsley are now nine points adrift of safety, while Birmingham climb to 14th and seven points off the play-off places.
Match-winner Hogan should have given the visitors the lead in the fifth minute, but he flicked Bellingham's corner over the bar despite being unmarked in the six-yard box.
Barnsley shaded the first half from that point on, with Jordan Williams, Callum Styles and Jacob Brown all drawing good saves from Birmingham goalkeeper Lee Camp before Conor Chaplin fired narrowly wide just before half-time.
But the hosts struggled to build on that pressure in the second half and failed to create any clear chances to equalise after Hogan had edged Blues ahead.
With relegation rivals Wigan and Charlton securing points on Tuesday, Gerhard Struber's Barnsley face a daunting task to avoid relegation, while Pep Clotet's Birmingham are now unbeaten in six Championship matches and nine in all competitions.
Barnsley manager Gerhard Struber told BBC Radio Sheffield:
"It is normal for young players to make mistakes. They have ups and downs in their performances.
"The last game against Sheffield (Wednesday) was very good from us. Today was a down. In the next game I hope for an up.
"It's a very difficult situation for the whole team and for me. We speak always about the same situations. We don't learn."
Birmingham City manager Pep Clotet told BBC WM 95.6:
"A win is always very welcome. It was a very difficult game to play because Barnsley were desperate for the points and the conditions were not the best for football. I'm very happy to see that the team can adapt.
"We knew that whoever would score first would have a big chance to win.
"We're very close to our first goal of the season: to stay in the league."
- 6AndersenBooked at 28mins
- 22OduorSubstituted forLudewigat 27'minutes
- 20StylesSubstituted forBähreat 45'minutes
- 28Simoes InacioSubstituted forThomasat 70'minutes
- 22BellinghamSubstituted forHardingat 88'minutes
- 15MonteroSubstituted forBelaat 70'minutes
- 10JutkiewiczBooked at 68minsSubstituted forDeanat 86'minutes
- Dean Whitestone
- Shots on Target
Second Half ends, Barnsley 0, Birmingham City 1.
Attempt blocked. Cauley Woodrow (Barnsley) left footed shot from outside the box is blocked. Assisted by Jacob Brown.
Corner, Birmingham City. Conceded by Michael Sollbauer.
Hand ball by Luke Thomas (Barnsley).
Foul by Michael Sollbauer (Barnsley).
Jérémie Bela (Birmingham City) wins a free kick on the left wing.
Substitution, Birmingham City. Wes Harding replaces Jude Bellingham.
Substitution, Birmingham City. Harlee Dean replaces Lukas Jutkiewicz.
Attempt missed. Lukas Jutkiewicz (Birmingham City) left footed shot from outside the box is too high. Assisted by Jérémie Bela.
Cauley Woodrow (Barnsley) wins a free kick in the defensive half.
Foul by Ivan Sunjic (Birmingham City).
Corner, Barnsley. Conceded by Marc Roberts.
Attempt blocked. Cauley Woodrow (Barnsley) right footed shot from outside the box is blocked. Assisted by Luke Thomas.
Goal! Barnsley 0, Birmingham City 1. Scott Hogan (Birmingham City) left footed shot from the centre of the box to the top left corner. Assisted by Jude Bellingham.
Attempt missed. Lukas Jutkiewicz (Birmingham City) header from the centre of the box misses to the left. Assisted by Jude Bellingham following a set piece situation.
Foul by Cauley Woodrow (Barnsley).
Jude Bellingham (Birmingham City) wins a free kick in the attacking half.
Alex Mowatt (Barnsley) wins a free kick on the left wing.
Foul by Lukas Jutkiewicz (Birmingham City).