Jen Beattie headed home Megan Campbell’s monster throw-in to snatch all three points at the Academy Stadium, while Izzy Christiansen bagged two from the spot, after Lucy Quinn had opened the scoring from 35 yards.
Nick Cushing’s side showed a real fighting spirit to claim a late victory against a well-organised Solihull outfit who had severely restricted the league champions’ chances.
Birmingham captain Kerys Harrop was sent off moments after the home side’s leveller, which turned the game in City's favour.
Marc Skinner’s side have proved a tough side to break down in recent visits to Manchester, holding the hosts to 1-1 draws in last season’s Super League campaign and the 2017 Spring Series.
Cushing’s side were victorious in the FA Cup Final meeting in May – but the pre-match talk indicated the test would prove similar to the league encounters.
That theory proved correct. After a period of early pressure, Birmingham broke the deadlock.
Rachel Williams had already poked wide before pressuring Ellie Roebuck. Quinn then collected the ball 35-yards out and curled into the top corner, despite the goalkeeper’s attempts to keep it out.
Although they dominated possession, City struggled to create in the opening 45 with Demi Stokes and Mel Lawley their most dangerous threats.
Jane Ross went close on two occasions but headed off-target, while Keira Walsh tried her luck from distance with a sweetly-struck half-volley which was pushed wide by Ann-Katrin Berger.
City continued to enjoy the share of the ball but did little to test the Birmingham goalkeeper.
Berger was called into action to deny Christiansen, who had been teed up by Jill Scott before the latter dragged a shot wide.
The home side were handed a route back into the game when Nikita Parris was upended by Rachel Williams and Christiansen stepped up to convert expertly.
With momentum behind them, the 'Shark Team' smelt blood and pushed for a winner. As the crowd - littered with inflatable sharks - urged them on, they found one.
Substitute Campbell – who had been introduced just minutes earlier – launched a trademark monster throw-in into the area and Beattie rose highest to head into the top corner, sparking delirium in the stands as the crowd belted out a chorus of: “That’s why we’re champions!”
There was further drama to follow in the seven additional minutes, as City were awarded another penalty – this one for Berger’s challenge on substitute Georgia Stanway. Christiansen stepped up once again to seal a stunning triumph - their sixth from six games.
How they lined up…
Roebuck took her place in goal, shielded by a back four of Stokes, Beattie, Steph Houghton and Abbie McManus.
Walsh protected the backline – just behind Christiansen and Scott, while Lawley and Parris operated on the wings. Ross led the line upfront.
City kick off their Continental Tyres Cup defence with a trip to Oxford on Thursday 2 November (7:45pm) before welcoming Everton to the Academy Stadium in the same competition on Sunday 5 November (6pm – after the men’s team play Arsenal).
Tickets are available at tickets.mancity.com or at the Etihad Stadium Ticket Office.