Birmingham won for the first time in 17 games as Sky Bet Championship play-off finalists Brentford's hangover continued into the new season with a 1-0 defeat at St Andrew's.
Jeremie Bela scored the 37th-minute goal that gave Blues their first win since February – and three points for new head coach Aitor Karanka – but they were equally thankful to debutant goalkeeper Zach Jeacock.
The 19-year-old Brummie – who kept £2million new signing Neil Etheridge on the bench – made a stunning double save in the second half, while Brentford hit the woodwork twice.
Blues started far better than in last week's Carabao Cup defeat to Cambridge and created the first chance.
Bela cut in from the left and rifled in a fierce drive that was superbly tipped around the post by goalkeeper Luke Daniels.
The visitors' first opening came soon after, however, when £5m striker Ivan Toney unleashed a firm angled drive that flew straight at Jeacock at the near post.
The Bees went closer when Josh Dasilva's low drive from the edge of the box bounced off the inside of the post and away.
The hosts scored when the unmarked Bela ghosted in to head home at the near post from Ivan Sanchez's corner for his first Sky Bet Championship goal of 2020.
Blues' former Brentford connection conjured up a chance which saw them go close to doubling their lead early in the second half.
Colin produced a brilliant cross and captain Harlee Dean got ahead of his marker to plant a flying header just wide.
Brentford went desperately close to equalising either side of the hour.
They hit the woodwork again when Canos' overhead kick crashed off the underside of the bar and into Jeacock's arms after the unmarked Ethan Pinnock headed Marcondes' free-kick across goal.
They were denied again with Marcondes the guilty party – unmarked for a stooping header palmed away by Jeacock, who foiled him again by blocking the follow-up shot.
Brentford found a way through when Dasilva released Mbeumo inside Kristian Pedersen, but the forward fired a tight-angled effort across goal and just wide.
The Bees missed another chance when captain Jansson headed wide from a corner, but Blues held on for a first victory since winning 1-0 at Barnsley on February 11.