Robbie Savage
BBC Radio 5 live at the iPro Stadium

The former Rams midfielder is not convinced by the red card one bit...

"You tell me, when's the clear goal-scoring opportunity there? Jake Buxton was in front of Loic Remy and when Remy got in front of him the keeper was there."

Andre Schurrle bends the free-kick over the top. That red card could well end the chance of a Derby comeback. There were no appeals from the Chelsea players.

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Former Southampton striker Kevin Phillips: "Let's just hope Sheffield United will not be camped out on the end of the box because if you do you would think Southampton would carve out the one opportunity they need and it would be heartbreaking for Sheffield United."

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Well I never! It's centre-half Jake Buxton who is dismissed! He does step across Loic Remy but that's a pretty standard bit of defending to be honest. Soft? Just a bit.

Chelsea on the counter, Eden Hazard slides in a pass for Loic Remy to chase. Lee Grant comes out to mop up, but did he handle outside the area? The linesman has his flag up...

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After a spell of Sheffield United pressure, Southampton are pushing now as the game enters the final 10 minutes but are still lacking in the final third. Mark Howard saved well from Sadio Mane's effort, but has otherwise had little to do. Time is running out for the Saints...

Derby sub Jordon Ibe beats two men with a cracking run before Cyrus Christie hammers a terrible cross out of play. Derby then make another change as Will Hughes is replaced by Jeff Hendrick. He has an eye for a goal from midfield too.

What a cracking finish from Craig Bryson, he scored a belter at Watford the other week as I recall and that is another class effort. Branislav Ivanovic was guilty of giving the ball away in the build-up. Sloppy.

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There it is! Derby do give us an entertaining finish! Lovely goal too at the end of a prolonged spell of possession. Johnny Russell sets the ball back to Craig Bryson, edge of the box, he doesn't thrash at it and side-foots the curler in off the far post. Petr Cech had no chance.

We have a game on!

Steve McClaren continues with his touchline coaching. An odd night for him to assess I guess- they haven't played badly, far from it, but at the same time Chelsea have been untroubled.

One Chelsea fringe player shines...

Rupinder Singh, external says: That was quite unexpected from Filipe Luis! Wonderful goal!

While another one... not so much...

Blues fan @Chelsea__MKN, external says: Andre Schurrle has just cemented his place on the bench with that performance. Get him off Jose!

Into the last 25 minutes. Derby need three goals and haven't looked like getting one. They've simply come up against a far stronger side tonight. Can they force one though and set up an exciting finale?

That is indeed that for Didier Drogba - he's off and Loic Remy is on for the final half hour.

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Former Southampton striker Kevin Phillips: "It was a great strike from Bobby Harris, Fraser Forster did well to smother it initially but a great reaction from the Sheffield United players, someone was going to get to it and it is no more than they have deserved. It was a great free-kick too. You are not going to get it up and down, only two players can do that, Ronaldo and Messi, I know Bobby well from our time at Blackpool and he decides to just go for it, hard and low."

Another injury concern for Chelsea? Didier Drogba loses his footing as he turns and instantly clutches at his ankle. He makes the 'substitution' sign. That could be that.

Andy (who we're assuming has seen more of him than Robbie Savage has) says: Will Hughes will be picked up by a top Premier League side very soon. If not January, then next summer, regardless of Derby County's promotion dreams.

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Upset o'clock? The home side take the lead and it is no less than they deserve, but it is a tad cruel on Fraser Forster. He pulled off a string of fine saves but fumbles Bob Harris's free-kick and Marc McNulty is there to get the ball over the line. Bramall Lane is in full voice!

I didn't know Filipe Luis had that in his locker to be honest. Great strike.

Derby respond by bringing on on-loan Liverpool winger Jordon Ibe for Simon Dawkins. Derby have just over 30 minutes to find a response.

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Special! Filipe Luis has his first goal for Chelsea and it's a typically Brazilian free-kick! The left-back takes aim from 25 yards, bends it effortlessly over the ball and soaring into the top corner. Wonderful hit, and Chelsea are heading into the semi-finals.

Image source, Getty Images

Robbie Savage
BBC Radio 5 live at the iPro Stadium

On Derby and England Under-21 midfielder Will Hughes...

"I don't remember much of him, he's only 19 now and I left Derby three and a bit years ago. I remember speaking to (former Rams boss) Nigel Clough, who rates him very, very highly. He was all the rage at one point, valued at £10m, but I've not seen him get to that next level yet."