Rudy Gestede's hat-trick took the goalscoring spotlight away from Jordan Rhodes as Blackburn kept up their late push to reach the Championship play-offs.
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The former Cardiff frontman notched a first-half hat-trick with three smart headers in a 4-2 win at Birmingham, as Blackburn stretched their unbeaten run to 10 games.
It was humiliating for Birmingham who trailed Gary Bowyer's visiting side 4-0 at half-time and now find themselves in a desperate survival battle.
Birmingham, with the worst home record in the Championship, were out of their depth in a frustrating first half and even second-half goals from Nikola Zigic and youngster Demarai Gray could not hide the problems they have.
They have now gone 16 games without a win at St Andrew's and were mercilessly tormented by Blackburn and Gestede's first-half finishing.
Even in the opening exchanges there were signs of what was to come when a confident Blackburn should have built up a commanding lead.
Clever work by Josh King resulted in a cross to the far post where the unmarked Gestede had the simple task of pushing the ball into the net but sent his effortt sailing over.
Gestede was openly apologetic to his colleagues and in the 10th minute redeemed himself and highlighted his danger with a superb goal.
King once again provided a clever lob to the far post and on this occasion the Blackburn striker athletically rose high to head into the near corner of the net.
Blackburn were quick to spot Birmingham's defensive shortcomings and it was hardly a surprise when they increased their lead in the 20th minute when Gestede was on hand to head home a King free-kick from the right.
Everything was going wrong for Birmingham and in the 22nd minute a Todd Kane shot was deflected into the net, with goalkeeper Darren Randolph going the wrong way, to give Blackburn an even more commanding lead.
A minute before the break Gestede completed his hat-trick when he headed home Craig Conway's corner from the left.
Gestede very nearly had a fourth goal five minutes into the second half when Randolph blocked another deflected shot after Rhodes, usually Blackburn's main goal threat, had set up the goalscoring opportunity.
Birmingham managed to pull back one goal in the 65th minute when Zigic rose above the Blackburn defence to head home a cross from Callum Reilly.
Substitute Zigic, who will be leaving Birmingham this summer, injected more life into the home side but the spirited fightback came too late to make amends for the first-half horror, despite teenager Gray adding a second goal six minutes from time.