Luton snapping into tackles as soon as the ball gets anywhere their box. All about keeping shape and denying the home side the space they want. Werner is sent to the turf by a hard but fair tackle. He's in for a battle.

Kepa has had his share of dodgy moments in a Chelsea shirt and he is put under a bit of pressure by a back-pass from Andreas Christiansen. He manages to get it clear before a team-mate pokes the ball out of play. Probably not a day to be trying anything too intricate at the back.

Karen Carney
Former England and Chelsea winger on BBC One

Luton are a difficult, hard working side, they will be defensive with a back five. It'll be interesting with Tammy Abraham and Timo Werner both in the side as to where they play.

Simon Sluga has no issue darting out of his box to meet a long ball forward ahead of Tammy Abraham and boot the ball clear. Good proactive keeping. The kind that has the old school fan watching through their fingers.

The home side get us under way.

Right then. The teams are out. Here we go...

Jimmy Floyd Hasselbaink
Former Chelsea striker on BBC One

I'd get the players out to warm up, get the legs going - you don't want to stand still and then play at 100 miles per hour

Luton playing in their home white shirts. Would have made things very interesting if the snow had continued to fall.

Well, it's not snowing quite so heavily anymore. Bit of a shame. Love the chaos that a bit of heavy snow brings to a game of football.

The teams are in the tunnel at the moment, so a bit of delay. They're still shifting snow on the pitch.

Chelsea

Chelsea boss Frank Lampard talking to BBC One: "A competition I give a lot to. I know not to take these games lightly. We need to find form individually.

"When you are in a tough moment, every game is an opportunity."

Danny Murphy
Former Liverpool and England midfielder on BBC One

Its a wonderful opportunity for Luton, a chance to make a name for themselves in front of the cameras and it is a free hit for them.

"After games it hits me the hardest. Everyone has someone they turn to, to discuss the game with and get things off their chest. Now I'm missing that."

Luton Town captain Sonny Bradley is set to face Chelsea in the FA Cup fourth round today, a little over a month on from suffering the loss of his father.

Bradley's "number one fan", Ray, a popular figure among Town supporters, died aged 57 in December after contracting Covid-19.

"My dad was a great man, if I could have picked anyone on the planet to be my dad I would have chosen him," Bradley, 29, told BBC Radio 5 Live.

"He was my biggest fan and I got a lot from him, especially when it came to football. I have a one-year-old and the best thing he left for me was a blueprint of how to be the perfect dad."

This is a really touching story. You can read the rest of it here.

Jimmy Floyd Hasselbaink
Former Chelsea striker on BBC One

The snow is a nightmare for the keepers! It's a strikers day today - get your shots away, and hopefully we see lots of goals.

It's not make or break for Frank, they need to give him time but he has a great opportunity today to put it right.

Image source, Getty Images

So what are Luton all about then? There are likely to be a few of you who only really pay attention to the Premier League, which means you're denying yourself the utter joy of the Championship and below.

I can tell you, though, that the Hatters are no mugs. They are currently 13th in the Championship and punching well above their weight. In Nathan Jones they have a savvy manager, who knows how to frustrate and hurt a superior opponent.

This season, they have beaten both Bournemouth and Norwich, both recent top-flight residents and two of the favourites to return there soon.

There won't be many who think Chelsea are going to slip up today. The stats certainly back up such a view. The Blues have progressed from 51 of their past 53 FA Cup ties against sides from a lower division.

However, as both Barnsley and Bradford fans know, there is always a chance of an upset.

If anyone needs a little reminder, have a look at the report from the 2015 Cup tie, when the Bantams pulled off a true shock.

That was a fun Saturday. Man Utd drew 0-0 at Cambridge and Middlesbrough knocked Man City out.

Image source, Getty Images

This is the first meeting between Chelsea and Luton since April 1994, when the Blues beat the Hatters 2-0 in the FA Cup semi-finals to reach their first final since 1970.

Gavin Peacock scored both the goals in that semi. He is now a Christian pastor in Canada. True story.

And it's live. Our coverage of Chelsea v Luton has just kicked in on BBC One, etc.

A reminder that the Chelsea v Luton game is one of two we have live on BBC TV today. Later, we'll also bring you Manchester v Liverpool (17:00 GMT kick-off).

Both games are on BBC One and the iPlayer. You'll also be able to watch them on this very page buy clicking the play button at the top.

As well as that, Radio 5 Live will be covering the FA Cup for much of the day. Their coverage gets under way at 11:30 and also includes commentary of Brentford v Leicester at 14:30.

Kevin Goddard: First time I've seen the mighty hatters on the beeb for a while! My two boys all set to cheer on Chelsea just to annoy me - just hope we keep it respectable!

Michael Reid: Havertz can't even get a game against Luton Town... So much for the £80m 'generational talent'

Fahad Khan: When was the last time we saw a 4-2-2-2 line up from a Premier League team ? Lampard being very ambitious with his tactics

Pretty sure Southampton did it yesterday, Fahad.