Welcome to our coverage of the FA Cup fifth round. Of course, for Andre Villas-Boas, this is about so much more than the FA Cup. It’s about strengthening his position, saving Chelsea’s season and potentially his job. Birmingham, however, will fancy their chances of an upset.

Villas-Boas asked is this a defining moment for him as Chelsea manager:

“Not at all.”

Four changes for Chelsea, five for Birmingham (mostly for the weaker):

Chelsea: Cech, Ivanovic, Cahill, Luiz, Bertrand, Ramires, Mikel, Meireles, Sturridge, Torres, Mata. Subs: Hilario, Essien, Lampard, Drogba, Malouda, Bosingwa, Kalou

Birmingham: Doyle, Carr, Davies, Ibanez, Murphy, Redmond, Fahey, Mutch, Elliott, Gomis, Rooney. Subs: Butland, Caldwell, Burke, Spector, Asante, Reilly, Jervis

And Chelsea get the game under way…

Stephen Carr’s afternoon is already over. He’s been injured in a challenge and has to limp off for Jonathon Spector.

Quiet enough so far as both sides feel their way into the game. We haven’t had a chance but some of the passing has been nice.

And, just as we type that, John Obi Mikel horribly misplaces a pass. Not quite as hirrible as the reaction from the crowd, though, who booed him loudly. Sign of the times at the Bridge.

GOAL! Chelsea 0-1 Birmingham City

And with the first real chance of the game, Birmingham expose just how soft Chel;sea are. A corner is swept over, David Luiz tries to head away but only diverts it back towards his own six-yard box. There are a few attempts at touches from both sets of players but, just yards out, left-back David Murphy is allowed a free shot and fires it home.

PENALTY to Chelsea!

More drama as Ramires is tripped in the box by Wade Elliot.

And it’s SAVED by Irishman Colin Doyle! Juan Mata hits it low hard and to the keeper’s right but Doyle springs across to touch it onto the post… and the first 20 minutes of this were dull!

“You’re getting sacked in the morning,” sing the Birmingham fans gleefully.

Chelsea do suddenly look a lot sharper, mind, and are passing the ball with much more purpose.

David Luiz really tests Doyle with a brilliant free-kick, curling from 25 yards and just about to dip under the bar.

Nathan Redmond – as ever – looking lively for Birmingham and dangerous on the break. Can’t be long until he finds himself in the Premier League.

Sturridge curls a teasing ball in but there’s a little too much on for Ivanovic as he surges at goal. A touch would have been enough to give Doyle trouble, surely.

Oh and now Sturridge goes close himself with a brilliant dipping volley from distance that’s just over. Think Cantona against Arsenal in 1995-96… except without it going in off the bar, obviously.

The Chelsea fans singing Jose Mourinho’s name.

The ball is skipped into the box, Torres can only help it on as he tries to control but it bounces up for Mata who powers a header a goal. Doyle, however, is equal to it.

HALF-TIME

The whistle is accompanied by boos as Chelsea go in one down and struggling to open up Birmingham, despite an improvement towards the end of the period.

This from Opta Sports:

50% – Chelsea have scored with only four of their eight penalties in all competitions this season. Squander.

Secodn half under way. Chelsea need a reaction… potentially to save the manager’s job.

Drogba comes on for Torres. Villas-Boas simply can’t afford to give the Spaniard the time.

It’s still Birmingham who are having the better of things here at the moment, challenging with a series of set-pieces.

GOAL! Chelsea 1-1 Birmingham

A Drogba-esque header from Daniel Sturridge from a fine Ivanovic cross. In off the post. Emphatic. And quite possibly very important in the long-term for Andre Villas-Boas.

There’s a bit of oomph about Chelsea now as they look so much more comfortable and there’s been a lift in the crowd.

Chelsea well on top now. After a series of dangerous balls across the box, Meireles almost puts them ahead via a deflection but it bounces just over.

Still in the mixer this one as Birmingham have weathered the Chelsea storm and just gone close. As we approach the 80, it’s much more open than at any point since the Birmingham goal.

According to ESPN, Drogba has had six touches since coming on… that’s over half hour.

Interesting – and potentially symbolic – change here as Lampard goes on for Mata. The crowd not impressed with the Spaniard being withdrawn.

Might have been a penalty to Chelsea as Ivanovic was challenged from behind in the box following a sweeping Drogba back-heel. Corner given.

And Redmond wastes a great chance to settle it! Put through on the left, he’s in on Cech but finishes weakly and straight into the keeper’s hands!

Free-kick at the edge of the box. Chance for Lampard and Chelsea… on multiple levels…

Lampard drives it straight into the well before the flag goes up for the subsequent chance.

FULL-TIME: Chelsea 1-1 Birmingham City

Boos at Stamford Bridge as Chelsea can’t eventually break down Birmingham. It’ll go to a replay. They did improve after a poor first period. It really is escalating to crisis point for Villas-Boas.