Match ends, Birmingham City 0, Sheffield Wednesday 1.
Sheffield Wednesday picked up a second win of the season to end Birmingham's unbeaten start.
The Owls enjoyed the better of the opening exchanges, with home goalkeeper Neil Etheridge making a fine stop from Adam Reach and Josh Windass hitting the crossbar with a free-kick.
Barry Bannan gave the visitors a deserved lead from the penalty spot after Callum Paterson had been fouled in the area.
Blues came closest when Owls defender Joost van Aken cleared Jonathan Leko's effort before debutant Jack Marriott fired just wide for the visitors.
The hosts thought they had scored a late leveller but Scott Hogan's celebrations were cut short by an offside flag.
A draw would have been harsh on Wednesday, who missed numerous chances in the first half before former Aston Villa man Bannan gave them the lead after the break.
This was a first defeat of the season for Aitor Karanka's men but they are also winless since the opening game of the campaign.
Sheffield Wednesday started 2020-21 with a 12-point deduction but have begun with just one defeat from their first five to give them hope of climbing away from danger.
Blues head coach Aitor Karanka:
"Today we had different players and we tried to be more offensive, but the lack of intensity - especially in the first half - made it difficult to attack and difficult to defend.
"We need to start games how we did at the beginning of the season, because when we do that, we have the intensity and we created more chances in 10 minutes than we have in three or four games in a row.
"I don't want to complain because it would be easy to say it wasn't a penalty or we could have scored one or two, but I need to know why we're making those mistakes.
"We're going to try to sort it out as soon as possible because this league is unforgiving."
Wednesday manager Garry Monk told BBC Radio Sheffield:
"I thought we dominated the game and were very unlucky not to have a second or third goal there.
"Today when we had that six minutes when we had to dig in and throw our bodies on the line Joost (van Aken) typified that with a block that he did.
"We deserved that today, we were dominant, very unlucky not to win by more and when we had to show the other side and dig in, we did that very well and got the clean sheet and three points.
- 20GardnerBooked at 66minsSubstituted forRobertsat 82'minutes
- 7CrowleySubstituted forMcGreeat 58'minutes
- 11BelaSubstituted forLekoat 67'minutes
- 19San José
- 4van Aken
- 7K Harris
- 45KachungaBooked at 74minsSubstituted forDele-Bashiruat 84'minutes
- 18WindassSubstituted forMarriottat 77'minutes
- 5PatersonSubstituted forPelupessyat 90+1'minutes
- Graham Scott
- Shots on Target
Second Half ends, Birmingham City 0, Sheffield Wednesday 1.
Offside, Birmingham City. Harlee Dean tries a through ball, but Scott Hogan is caught offside.
Attempt missed. Harlee Dean (Birmingham City) left footed shot from outside the box misses to the right. Assisted by Riley McGree.
Substitution, Sheffield Wednesday. Joey Pelupessy replaces Callum Paterson.
Attempt saved. Scott Hogan (Birmingham City) right footed shot from the centre of the box is saved in the centre of the goal. Assisted by Riley McGree with a headed pass.
Attempt missed. Jack Marriott (Sheffield Wednesday) right footed shot from a difficult angle on the right is close, but misses to the left. Assisted by Massimo Luongo with a headed pass.
Attempt missed. Adam Clayton (Birmingham City) right footed shot from outside the box is high and wide to the right. Assisted by Jonathan Leko.
Attempt missed. George Friend (Birmingham City) left footed shot from the left side of the box is too high following a corner.
Corner, Birmingham City. Conceded by Joost van Aken.
Attempt blocked. Jonathan Leko (Birmingham City) left footed shot from the centre of the box is blocked. Assisted by Scott Hogan with a cross.
Attempt missed. Adam Reach (Sheffield Wednesday) left footed shot from outside the box misses to the right.
Substitution, Sheffield Wednesday. Fisayo Dele-Bashiru replaces Elias Kachunga because of an injury.
Foul by Riley McGree (Birmingham City).
Callum Paterson (Sheffield Wednesday) wins a free kick in the defensive half.
Substitution, Birmingham City. Marc Roberts replaces Gary Gardner.
Attempt missed. George Friend (Birmingham City) header from the centre of the box is close, but misses to the left. Assisted by Iván Sánchez with a cross following a set piece situation.
Iván Sánchez (Birmingham City) wins a free kick on the right wing.
Foul by Kadeem Harris (Sheffield Wednesday).
Foul by Riley McGree (Birmingham City).