Birmingham came from behind to beat Blackburn with second-half goals from Robbie Blake and Emile Heskey.
Substitute Blake produced a calm finish to steer the ball past Brad Friedel to round off a flowing move.
And with 10 minutes left Heskey hit a half-volley past Friedel after some some hesitant Blackburn defending.
Jonathan Stead had given Blackburn a surprise first-half lead when he headed past Maik Taylor following a Brett Emerton cross from the right wing.
Having won on their previous three visits to St Andrews, Blackburn looked like they might secure an improbable fourth triumph once Stead had put them in front.
Until Blake's goal, Birmingham's attacks repeatedly foundered on the twin peaks of Blackburn's defensive resolution and Friedel's authorative goalkeeping.
Along with Pennant, Pandiani had a good game for Birmingham, the club's recent signings working well in tandem, notably when the Uruguayan striker hit the woodwork.
A Pennant corner found Pandiani at the far post and the former Deportivo la Coruna striker crashed a volley against the inside of the post after quickly controlling the ball with his chest.
Pennant then picked out Pandiani with a free-kick though Friedel easily gathered the Birmingham striker's header.
Another Pennant cross also forced Friedel into a sharp save from Ryan Nelson's misdirected header.
Initially Blackburn struggled to get the ball to Stead, who was playing as a lone striker.
But on 11 minutes Stead picked up the ball on the edge of the box and found Emerton lurking on the right wing.
Emerton whipped the ball into the Birmingham area where the unmarked Stead powered a header past Taylor.
Just before the interval Emerton sent Stead clear but the Blackburn striker proved less adept with his feet, blazing wildly over.
Despite that setback Birmingham quickly reestablished their attacking momentum, with Pennant's foraging runs down the right causing the Blackburn defence repeated problems.
Twice he delivered tantalising crosses to the near post and twice Pandiani was just unable to deliver the finishing touch.
Aaron Mokoena's crude body check on Pennant, which earned the South African a yellow card, illustrated the difficulties the fomer Arsenal winger was giving Blackburn.
Robbie Blake's introduction by manager Steve Bruce proved an inspired substitution just before the hour mark.
Good link-up play between Stan Lazaridis, Pandiani and Heskey set up Blake, who calmly curled the ball past Friedel.
With Blackburn barely able to muster an attack, Birmingham continued to press for the winner.
And following Blackburn's inability to clear the ball, Heskey rifled a half-volley past Friedel.
Birmingham boss Steve Bruce:
"Emile Heskey has had his critics, with me also coming under fire for signing him.
"But he has done fantastically well for us all season and without him we might have been in a bit of trouble.
"If you're looking for a typical English centre-forward who is a target man, then there is no-one better than Heskey in this country."
Blackburn boss Mark Hughes:
"They didn't want Robbie Savage to play. They said it was a security issue, but it was a footballing one.
"I phoned Steve (Bruce) and asked him about playing Robbie, but he didn't want him to.
"It would've been an opportunity to put everything behind both clubs."
Birmingham: Maik Taylor, Melchiot, Cunningham, Upson,
Lazaridis, Pennant, Johnson, Nafti (Blake 59),
Anderton (Clemence 22), Heskey, Pandiani (Morrison 84).
Subs Not Used: Martin Taylor, Vaesen.
Booked: Heskey, Morrison.
Goals: Blake 61, Heskey 80.
Blackburn: Friedel, Neill, Todd, Nelsen, Johansson (Tugay 67),
Emerton (Gallagher 76), Reid, Mokoena, Flitcroft,
Pedersen (Thompson 59), Stead.
Subs Not Used: Short, Enckelman.
Booked: Mokoena.
Goals: Stead 13.
Att: 28,621.
Ref: B Knight (Kent).