• How did they get here?

They finished second in Group C, before overcoming Genk and then, somewhat impressively, Sevilla, aka the 'Stephen Hendry of the Europa League'.

• What's the big chat?

They got off the ground in 1892 (pre internet) and their first professional manager was John Madden - no, not that one - the former Celtic player who is known as the 'The Father of Czech Football' having helped Slavia win four Czechoslovak titles.

• Have they ever won any big European trophies?

Not really, unless you count the 1938 Mitropa Cup.

• Any former players you might of heard of?

Patrik Berger - ex of Liverpool's 2001 Uefa Cup winning team. Vladimir Smicer - ex of Liverpool's 2005 Champions League winning team. There possibly might be some scouts from Merseyside in Prague tonight.

Head-to-head

• Arsenal and Napoli have met just twice before in Europe - home and away in the group stages of the Champions League in 2013-14. Arsenal defeated the Italian side 2-0 at Emirates Stadium, before losing by the same scoreline at the Stadio San Paolo.

Arsenal

• Arsenal have reached the quarter-final stages of European competition in consecutive seasons for the first time since 2008-09/2009-10 in the Champions League.
• The Gunners knocked out CSKA Moscow at this stage of the Europa League last season (6-3 on aggregate) before falling to Atletico Madrid in the semi finals.
• Arsenal have been beaten just once in their last 17 home games in the Uefa Cup/Europa League (W12 D4) - losing 1-2 to Ostersunds FK in the last 32 in 2017-18.

Napoli

• Napoli have reached the quarter finals of the Uefa Cup/Europa League for the third time in their history. They fell at the semi-final stage in 2014-15, but won the competition in 1988-89 with a side featuring Diego Maradona.
• They have never beaten an English side away from home in European competition (P8 W0 D1 L7) - they have previously lost in such games against Burnley, Leeds United, Liverpool, Chelsea, Manchester City and Arsenal.

Joe Wedgwood: Buzzing to see Rambo, Auba, Laca all start but Cech worries me! Just play your No.1!!!

Watford stuck with Gomes.

Arsenal boss Unai Emery to BT Sport: "They have very good players. They have very offensive players. We need to control the passes and spaces. We need to control the match. We know it will be difficult."

Image source, Rex Features

Charlie Edlesten: Got to be Chelsea,we have so far had the easy draws and we've played well in the Europa League,would be a waste to not go on and win it and qualify for the Champions League one way or another.

So is Kane out for the season? And maybe even England's Nations League tournament?

Here's the Spurs statement: "Following assessment over the past two days, we can confirm that Harry Kane has sustained a significant lateral ligament injury to his left ankle following a challenge in our Champions League quarter-final, first leg win against Manchester City.

"Investigations are ongoing and he will continue to be assessed by our medical staff over the coming week."

And there's more...

"We can also confirm that examinations have revealed that Dele Alli fractured his left hand during Tuesday's fixture.

"The England midfielder will now be assessed to determine his availability for this weekend's fixture against Huddersfield Town."

Elsewhere, ce soir (BST time) Benfica are at home to Eintracht Frankfurt.

And Villarreal face Valencia in the historic all 'V' tie.

The moment Tottenham fans watched their key striker Harry Kane leave the pitch injured against Manchester City was a bit like finding out that there will be no more episodes of Fleabag, or that the milk you thought would be OK in the fridge for one more day, wasn't.

Heart sinking.

Head-to-head

• This will be the first competitive meeting between Slavia Prague and Chelsea. The Czech side have won just one of their previous nine games against English sides in Europe (D2 L6) - this coming against Leeds United in March 2000 in the Uefa Cup (2-1).

Slavia Prague

• That home victory over Leeds was Slavia Prague's most recent game in a European quarter-final; they were eliminated having lost the first leg 0-3 at Elland Road. Their only progression from a European quarter final was in the 1995-96 Uefa Cup against Roma (3-3 on away goals).

Chelsea

• This is Chelsea's 10th European quarter-final since 2003-04. The Blues have progressed from nine of those ties, only being eliminated by Manchester United in the Champions League in 2010-11.
• Chelsea have won more games (nine) and have a better goal difference (+21) than any other side in the Europa League this season.
• Chelsea striker Olivier Giroud is the top scorer in this season's Europa League with nine goals. The last player to surpass this figure in a single Europa League season was Aritz Aduriz, who netted 10 goals for Athletic Bilbao in 2015-16.

Slavia Prague have made five changes to the side that thrashed Dukla in the Czech league in their last match.

Slavia Prague: Kolar, Coufal, Olayinka, Ngadeu­-Ngadjui, Stoch, Boril, Deli, Sevcik, Traore, Masopust, Kral

Subs: Kovar, Zmrhal, Husbauer, Van Buren, Kudela, Skoda, Frydrych

Maurizio Sarri has made seven changes to his Chelsea side that beat West Ham in their last outing.

Eden Hazard drops to the bench while Olivier Giroud returns to the starting line up to maintain his run in the team on European nights.

Chelsea: Kepa, Azpilicueta, Rudiger, Christensen, Alonso, Jorginho, Barkley, Kovacic, Pedro, Willian, Giroud

Subs: Caballero, Kante, Higuain, Hazard, Loftus-Cheek, Zappacosta, Luiz

Image source, BBC Sport

Arsenal make five changes from the side who lost 1-0 to Everton. Pierre-Emerick Aubameyang has recovered from a recent illness and partners Alexandre Lacazette up front.

Defender Laurent Koscielny is back from a foot injury and starts, as do midfielders Lucas Torreira and Aaron Ramsey. Petr Cech is back in goal from Bernd Leno.

Mesut Ozil keeps his place, but Henrikh Mkhitaryan drops to the bench.

Napoli make three changes to the side who drew 1-1 with Genoa. Lorenzo Insigne is back in the starting line-up after a thigh injury, with Alex Meret starting in goal and Mario Rui back in the team.

Goalkeeper David Ospina is on the bench against his parent club. No rules stopping loanees playing against their club in Europe.

Arsenal: Cech, Sokratis, Koscielny, Monreal, Maitland-Niles, Torreira, Ramsey, Kolasinac, Ozil, Lacazette, Aubameyang.

Napoli: Meret, Hysaj, Maksimovic, Koulibaly, Mario Rui, Callejon, Allan, Fabian Ruiz, Zielinski, Insigne, Mertens.

Image source, .

Rezaa Sait: Arsenal will go the furthest. Emery is a Europa League specialist.

Pierre-Emerick Aubameyang starts for Arsenal having fully recovered from a recent illness.

Full team news to follow.

And why....

Thoughts posted using #bbcfootball, external

Image source, EPA

Perhaps the key to the Gunners overcoming a strong Napoli side will be whether the club's leading scorer this season Pierre-Emerick Aubameyang is at full fitness.

Illness has restricted the forward to substitute appearances in Arsenal's past two Premier League matches.

Here's what gaffer Unai Emery has had to say:

"He's getting better and can start.

"He had a small problem and he has taken antibiotics for his illness.

"That's the main reason he didn't start those two matches."

Emery also revealed that he will wait until match day to assess the fitness of Laurent Koscielny who has been recovering from a foot injury, and Granit Xhaka, who is getting over a groin problem.

Team news coming up faster than Auba chasing a through-ball.

Eden Hazard starts from the bench.

Full team news to follow.