Fulham striker Collins John put the Dutch ahead when Liam Ridgewell failed to cut out Edson Braafheid's cross.
Birmingham hit back as Liam Ridgewell bundled in James McFadden's cross and survived three late David Ngog chances.
The visitors had been denied the lead when Yakubu's shot was cleared off the line by Liam Ridgewell.
John found the net from close range after Ridgewell failed to deal with Braafheid's dangerous cross from the left.
Birmingham were unlucky when a header from Liam Ridgewell was disallowed late on despite the ball crossing the line.
Davies will emulate midfielder Craig Gardner and defender Liam Ridgewell as former Villa players plying their trade across the city.
And they had a great chance to equalise when Ridgewell was through on goal after an angled run from the left flank.
They were given a nervous 25 minutes when Ridgewell beat Wigan's offside trap to flick a deflected cross from Barry past Filan.
He has only three centre-backs now at his disposal in Roger Johnson, Martin Jiranek and Ridgewell, who has been operating primarily at left-back.
Prior to Torres' substitution, Steven Gerrard had given Liverpool the lead early in the second half, but Liam Ridgewell quickly pulled Birmingham level.
Just before the break Blues striker Marcus Bent was denied a penalty while Kightly saw his effort cleared off the line by defender Liam Ridgewell.
The visitors really should have set up a tense finale when a close-range header from Ridgewell trickled fractionally over the line before being scrambled clear by James.
Maynor Figueroa rifled a shot wide for Wigan before Liam Ridgewell headed wide at the other end, and Foster saved low down after N'Zogbia tried his luck.
However, Blues keeper Ben Foster smartly got a hand to the ball to crucially slow down the Nigerian's left-foot shot before a sliding Ridgewell cleared off the goal-line.
Davies will hope he can make the same impact as Ridgewell and Gardner, who were only fringe players at Villa but have become key components of the Blues side.
The Scottish midfielder tip-toed around three defenders and curled in a delightful ball to the back post for the unmarked Ridgewell to bundle the ball in with his thigh.
His delightful ball inside the full-back teed up Liam Ridgewell for a low cross from the byeline, which Matt Derbyshire could only poke wide from inside the six-yard box.
Fittingly given his impressive start it was McIndoe who gave Doncaster the lead after Ridgewell was adjudged to have handled the ball in the area following a James Coppinger's cross.
BBC: SPORT | Football | League Cup | Doncaster 3-0 Aston Villa
First Holland goalkeeper Boy Waterman failed to deal with a free-kick and the ball fell to Liam Ridgewell, but his shot on the turn was deflected wide by John's outstretched leg.
With 12 minutes to go the former Sunderland midfielder skipped over a couple of Villa tackles, before his powerful shot took a deflection off the hapless Ridgewell to arc over Sorensen.
BBC: SPORT | Football | League Cup | Doncaster 3-0 Aston Villa
The second half was proving to be a much livelier affair and Birmingham's scorer almost turned provider as Ridgewell crossed into Bowyer from the left but the unmarked midfielder fluffed his volley.
Liam Ridgewell, possibly distracted by Johnson's return, allowed Hoilett to nick the ball off his toes and the Canadian youngster coolly took the ball past Foster and slotted into an empty net.
Bruce has signed nine players this summer as he bids to keep Birmingham in the Premier League, but only four - Fabrice Muamba, Garry O'Connor, Stuart Parnaby and Liam Ridgewell - are British.
And five minutes later he put Arsenal in the lead after seizing on a mistake from Liam Ridgewell, drifting past two City defenders and rifling his low effort past the reach of Taylor.
After Craig Gardner dragged a free-kick wide and Cameron Jerome's header was cleared off the line by Sears, the Blues got the goal their improvement warranted as Ridgewell beat Winston Reid to a corner and thumped in a header to send the travelling fans wild.
He had already badly miscued an effort wide from a Liam Ridgewell cross and then seen Gordon save well with a foot after he had run clear on goal before once again finding himself with only the keeper to beat but this time finding a finish of quality to side-foot inside the far post.
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