Liverpool cruised through to their 22nd FA Cup semi-final via their biggest ever away win in the competition as Rafael Benitez's side piled on the agony for Birmingham manager Steve Bruce.

City have proved to be a thorn in the side of the Reds and unbeaten against them in their last four league meetings.

But their severely depleted line-up, with Emile Heskey and Nicky Butt the latest to join the casualty list, were simply no match for the Merseysiders, who have now scored 14 goals in their last three games.

Two-goal Crouch in particular ruthlessly exposed non-existent marking and Steven Gerrard, who created three of the goals, and the goggle-wearing Mohamed Sissoko took full advantage of acres of space in midfield.

With confidence at rock bottom and big name players sidelined, on this evidence Birmingham look doomed to life in the Coca-Cola Championship barring a miracle - with Manchester United and Chelsea next up.

In contrast to the treatment dished out by Aston Villa fans to David O'Leary, the Birmingham followers have remained loyal to Bruce - although one fan ran across the pitch to try to confront him after the third goal tonight, before being shepherded away by stewards.

But the pressure will inevitably mount after such a hammering even though the board have continually given their backing to the former Manchester United star.

Liverpool made six changes from the side which had won at St. James' Park and their line-up included Sissoko - wearing goggles to protect the serious eye injury he suffered against Benfica only a month ago.

Any hopes that Birmingham had of a morale-boosting win to aid their Barclays Premiership survival hopes were shattered inside the first four minutes as Liverpool struck twice through Sami Hyypia and Crouch after some appalling defensive play.

The City marking was non-existent when an inswinging free-kick by Gerrard was flicked on by Sissoko to leave Hyypia with a free header - and he made no mistake from close range after just 54 seconds.

The stunned home supporters had not recovered from this setback when they found themselves 2-0 down with Gerrard again involved.

This time the England midfielder surged down the right flank and his powerful and dipping cross curled around the back of the Birmingham defence and left Crouch with the simplest of headers from close range.

Blues were in total disarray at this juncture and it seemed Liverpool might score almost everytime they ventured forward.

Crouch flashed a powerful drive just wide and was only inches away from connecting with another dangerous centre from Marcos Painter.

In a rare moment of danger for the visitors, Jamie Carragher produced an excellent block tackle to deny Mikael Forssell from Jermaine Pennant's low cross.

Benitez was forced to make a change after 21 minutes with Djimi Traore limping out of the action to be replaced by Harry Kewell.

But it made no difference to Liverpool's dominance and after 38 minutes Crouch struck for the second time with his 12th goal of the campaign.

The Blues defence could not cope with a mazy run from Luis Garcia before he slipped the ball into the path of Crouch who tucked away his shot from 12 yards out.

Blues rallied briefly at the start of the second period but the goals soon started to flow again.

Substitute Fernando Morientes had the simplest task to net number four just before the hour mark from Gerrard's pass and a stinging 25-yard drive by John Arne Riise nine minutes later made it 5-0.

Birmingham's misery was added to in the 77th minute when half-time substitute Olivier Tebily sliced a Kewell cross into his own net.

Then in the 90th minute substitute Djibril Cisse made it 7-0 when his deflected shot skidded underneath the body of Maik Taylor - via a deflection off Blues' Painter.

Teams:

Birmingham Maik Taylor, Melchiot, Cunningham,Martin Taylor (Tebily 45), Painter, Pennant,Johnson (Bruce 75), Clemence, Clapham, Forssell,Dunn (Kilkenny 71).

Subs Not Used: Vaesen, Lazaridis.

Booked: Clemence, Johnson, Bruce.

Liverpool Reina, Finnan, Carragher, Hyypia,Traore (Kewell 22), Alonso, Gerrard (Cisse 71), Sissoko, Riise,Crouch (Morientes 56), Luis Garcia.

Subs Not Used: Dudek, Kromkamp.

Goals: Hyypia 1, Crouch 5, 38, Morientes 59, Riise 70,

Tebily 77 og, Cisse 89.

Att: 27,378

Ref: R Styles (Hampshire).