Postpublished at 19:30 GMT 16 January 2019
Ronnie Radford!
Watch game on BBC One and listen on BBC Radio 5 live
Keogh scores winning spot-kick to set up tie with Accrington in round four
Saints led 2-0 through Armstrong and Redmond strikes
Wilson free-kick reduces the deficit before Waghorn heads in
Derby's Bryson earlier had finish ruled out by VAR for narrow offside call
Tom Rostance
Ronnie Radford!
Southampton v Derby (19:45 GMT)
BBC One
Tonight's game is streamed live at the top of this very page, or you can watch a bit of live TV like the old days if you hit BBC One on your remote.
Gary Lineker is joined by Alan Shearer and Jermaine Jenas in the studio, while Danny Murphy is in the co-comms seat.
It's all starting any minute now...
#bbcfootball or text 81111 (UK only)
Wolves have come a long way - City too. Although one man remains a constant!
Image source, Twitter
Image source, TwitterSouthampton v Derby (19:45 GMT)
Image source, Getty ImagesDerby have also won the FA Cup once - back in 1946 when they thrashed Charlton 4-1 in extra-time.
They haven't reached a quarter final in 20 years though.
Southampton v Derby (19:45 GMT)
Southampton: Gunn, Cedric, Stephens, Vestergaard, Ramsey, Romeu, Ward-Prowse, Elyounoussi, Armstrong, Johnson, Long. Subs: McCarthy, Redmond, Gallagher, Targett, Bednarek, Slattery, Barnes.
Derby: Roos, Bogle, Keogh, Tomori, Malone, Bryson, Huddlestone, Mount, Waghorn, Marriott, Wilson. Subs: Carson, Lawrence, Evans, Bennett, Holmes, Lowe, Nugent.
Referee: Anthony Taylor (Cheshire)
Watch some of the best goals from the third round of the FA Cup, including Nathan Redmond's fine effort from 25-yards out for Southampton.
Watch all the FA Cup third-round goals here.
Available to UK users only.
Southampton v Derby (19:45 GMT)
Simon Brotherton
Commentator on BBC TV
This was one of the better ties in the third round, and both will still feel they have a decent chance of going through.
Southampton, who reached the semi-finals last year, appeared to be cruising at Pride Park with a 2-0 lead before the Championship side fought back and might even have won it with the last kick of the game.
Ralph Hasenhuttl will try to balance some rotation with the desire to continue their recent confidence-building form, while Derby will be keen to bounce back from last Friday's disappointing result at Leeds and the whole 'spy-gate' saga surrounding it.
Southampton v Derby (19:45 GMT)
Image source, Getty ImagesFrank won the FA Cup on four occasions with Chelsea - scoring the winner in 2009
Derby County manager Frank Lampard: "It's important for us. We love the FA Cup, and the fans do, too.
"It's another opportunity for the players to show what they can do against a good Premier League team."
Southampton v Derby (19:45 GMT)
Southampton have won the FA Cup once in their history - back in 1976 - and have lost three more finals, most recently in 2003.
They also reached the last four last season.
#FAPeoplesCup
The sides playing tonight are hoping ultimately to get to the FA Cup final in May - and YOU can too!
The FA People's Cup gives you the chance to play at St George's Park and appear on the Wembley turf during the FA Cup final in May.
Here's Alex Scott to explain...
Register now for the 2019 FA People's Cup!
So what are you waiting for? Find out more about the competition and how to sign up here.
Southampton v Derby (19:45 GMT)
Alan Shearer
Former England captain on BBC One
Southampton have made a huge improvement, they have totally changed their style of play. They beat Arsenal convincingly and you saw his [Hasenhuttl] style of play.
He likes to close sides down and the players are saying that they understand what he wants them to do with and without the ball.
They looked lost under Mark Hughes - they didn't have any ideas.
#bbcfootball or 81111 on text (UK only)
Very impressed that the new Saints boss is giving academy players and British players in general more opportunities in the early days of his tenure.
Shaun, Somerset
Southampton v Derby (19:45 GMT)
Image source, Getty Images...Accrington away!
If you've not stood in the sleet on Accy's away terrace - sans roof - are you even a real football fan?
A proper ground, a proper game awaits the winners in round four.
Southampton v Derby (19:45 GMT)
Derby manager Frank Lampard to BBC Sport:
Any comments to make about Bielsa? "No, I made quite a few comments this week, I haven't seen the latest press conference. It's one to comment on later when I know more about it. It's also a huge game for us tonight, let's focus on that.
"It would mean a lot for us to go on a cup run, I grew up with it, I know what it means to fans.
"We are searching for form, it's been a difficult run."
Southampton v Derby (19:45 GMT)
Southampton
Southampton manager Ralph Hasenhuttl to BBC Sport: "We are well prepared for this game, we have a few youngsters on the pitch and it is a good chance to see them. I am looking forward to this game.
"I am very pleased so far. We took some important points but it is still a very close situation. We have made some good steps but we need more steps.
"We will go as far as posible but there is no doubt that the focus is on the Premier League - to stay in the league is more important for the club."
#bbcfootball or 81111 on text (UK only)
You've all probably seen this '10-year challenge' that has been doing the rounds on social media, where you post an embarrassing photo of yourself in 2009 and an equally unflattering one from now and laugh at how the aging process and the non-stop misery of modern life has ravaged your youth.
Well, we want the same from you now - but about the club you love.
Image source, Getty ImagesThis week 10 years ago Southampton took a beating at home to Doncaster - on their way to relegation to League One...
Send us an image to sum up supporting your team in 2009 - and one which sums up now. Good or bad, optimistic or pessimistic - send them in to #bbcfootball
Image source, Getty ImagesDerby have had a slightly less traumatic, less interesting? - 10 years. They haven't left the Championship.
Southampton v Derby (19:45 GMT)
Image source, Getty ImagesSouthampton manager Ralph Hasenhuttl: "I think both teams in the moment are in a very important period in the season. For both teams, it's [the replay] not the best thing.
"The best thing for us is that we have three suspended players at the moment and all three can't play tonight, but they can play on Saturday.
"That's the positive and the most perfect thing from the FA Cup game."
Image source, PADerby manager Frank Lampard "does not believe" spying tactics were employed during his time as a Chelsea player.
The Football Association is investigating Leeds head coach Marcelo Bielsa, who admitted sending a member of staff to 'spy' on Derby training.
Ex-Blues coach Andre Villas-Boas reportedly said he would secretly watch opposition train during his time at Stamford Bridge under Jose Mourinho.
"I certainly wasn't aware of it and I don't believe it at all," said Lampard.
"Certainly not in the form that it happened this time."
Southampton v Derby (19:45 GMT)
BBC Radio 5 live
If my words don't float your boat, or you can't see the match on BBC One/above, you can also listen to full match commentary from 5 live tonight.
Just press play above to hear Ali Bruce-Ball and former Manchester City midfielder Michael Brown.
Southampton v Derby (19:45 GMT)
BBC One
Tonight's game is streamed live at the top of this very page, or you can watch a bit of live TV like the old days if you hit BBC One on your remote.
Gary Lineker is joined by Alan Shearer and Jermaine Jenas in the studio, while Danny Murphy is in the co-comms seat.