Champions League Tuesday sees London's representatives in Europe's premier club competition go head-to-head with Ruhr rivals Borussia Dortmund and Schalke. Sky Sports takes a look at how Arsenal and Chelsea compare with their German opponents in terms of their history, the present and their hopes for the future...
Ground (Capacity): Emirates Stadium (60,361)
League titles: 13
European best: Runners-up (2006)
The Gunners were formed 127 years ago as Dial Square and established themselves as a major force in English football under Herbert Chapman as they won the FA Cup for the first time in 1930. Five league titles followed in the 1930s and in 1971 they became only the second team of the century to do the Double. Arsenal moved from Highbury to the newly-built Emirates Stadium in 2006 and their status in European football is reflected by the fact they have reached the knockout stages (or second group stage) of the Champions League for each of the past 13 seasons under Arsene Wenger - a record only matched by nine-time winners Real Madrid.
Ground (Capacity): Westfalenstadion (80,720)
League titles: 8
European best: Winners (1997)
Dortmund were founded in 1909, re-established as BVB in 1948 and entered the first season of the Bundesliga in 1963 as the German champions. The famous Westfalenstadion was opened in 1974 and is now the biggest stadium in Germany but the club was dogged by financial problem for much of the next decade before rising to prominence again in the 1990s, most notably as Champions League winners in '97 thanks to a 3-1 win over defending champions Juventus. More money issues saw BVB struggle through the early part of the 21st century before re-emerging to claim back-to-back Bundesliga crowns under Jurgen Klopp in 2011 and 2012.
Ground (Capacity): Stamford Bridge (40,387)
League titles: 4
European best: Winners (2012)
Chelsea won their first English league title in 1955 under manager Ted Drake and enjoyed cup success under Dave Sexton in the 1970s before spending time in the second tier for parts of the next decade as their struggles belied the club's glamorous past and attractive west London location. The team became a cosmopolitan outfit under Glenn Hoddle, Ruud Gullit and then Gianluca Vialli winning trophies at home and abroad before the arrival of billionaire Russian owner Roman Abramovich took the club to the next level. Back-to-back league titles under Jose Mourinho followed and in 2012 Chelsea became the first London club to be champions of Europe.
Ground (Capacity): Veltins Arena (61,973)
League titles: 7
European best: Semi-finalists (2011)
Schalke were the dominant team of German football throughout the 1930s, winning six of their seven titles by 1942. Titles have been harder to come by since then with the last coming in 1958 - five years prior to the establishment of the Bundesliga - but the club remains hugely popular and second only to Bayern Munich in terms of membership. The Gelsenkirchen-based side has won the German Cup three times since the turn of the century and had their best ever run in the Champions League under Ralf Rangnick in 2011 before falling to Manchester United in the last four.
The French coach was regarded as a shock appointment as Arsenal boss in 1996 when he became the third non-British manager of the Premier League era but is now the grand old man of management in England with a reputation for attractive football. Having spent more than 17 years in charge of the Gunners (the next longest-serving top-flight boss is Alan Pardew, who has yet to complete three years at Newcastle), he has led the team to three Premier League titles. Two of those were part of Doubles and the other victory is remembered as the work of The Invincibles - the first English team since Preston North End in 1889 to go an entire league season without defeat. Wenger has supporter criticism in recent seasons for his failure to develop the side but after a strong start to the current campaign, he is enjoying something of a renaissance and renewed hope of a successful title challenge after going eight years without a trophy.
Until 2008, Klopp was a one-club man having played his entire career for FC Mainz before going on to manage them for seven years. But five years ago all that changed as the effervescent coach embarked upon what would turn out to be an astonishing adventure with BVB - winning the title in 2011. Despite losing star player Nuri Sahin to Real Madrid, the following season would go down in history as Dortmund set a record points tally in the Bundesliga with his young side playing an exciting brand of high-tempo transition football. Klopp showed his remarkable ability to regenerate the team when he survived the loss of Shinji Kagawa to Manchester United to take Dortmund to the Champions League final in 2013, only losing out to Arjen Robben's late goal. After another summer of shrewd signings, Klopp is building again.
Mourinho is regarded as one of the greatest coaches of the modern era, having won the Champions League with both Porto and Internazionale - the first of those triumphs coming at the age of just 41. The Portuguese also broke Barcelona's dominance of La Liga by claiming the Spanish title with Real Madrid in 2012 and thus becoming the first manager or player to win the league in England, Italy and Spain. It is thanks to his time in England with Chelsea that Mourinho is known as 'The Special One' after ending Chelsea's near 50 year wait to be crowned champions of England. Now back at Stamford Bridge for a second spell, his emphasis on solid defence and dressing room unity will give supporters hope of a bright future - if he can maintain a working relationship with owner Abramovich.
Keller stepped up from the role of youth team coach at Schalke in December following the sacking of Huub Stevens to a lukewarm response from supporters. Within weeks, the interim coach was having to deal with 'Keller out' banners and a home defeat to Greuther Furth only worsened the mood. But the 42-year-old responded by making some changes and leading the team to eight wins from the final 12 games of the season - including a Revierderby win over Dortmund - to ensure a fourth-place finish and Champions League qualification. Keller was subsequently rewarded with a contract extension but following a mixed start to the current campaign, question marks remain over his ability to succeed at Schalke in the long term.
The German playmaker is widely acknowledged as one of the game's most gifted footballers so it was a disappointment to Real Madrid players and fans alike when club president Florentino Perez agreed to sell Ozil to Arsenal in the summer. The 25-year-old left-footed midfielder has made an instant impact at the Emirates, showcasing that rare ability not only to perform himself but also raise the standards of those around him thanks to his effective use of space.
Wenger says: "His skill, his finishing, it's what you want to see in the stand when you come and watch football. Just sit there and enjoy it. I loved him when he was at Madrid, I thought he was great there. We are lucky to have got him."
While Mario Gotze left Dortmund in the summer and Robert Lewandowski looks set for the exit too, the club continues to produce players of exceptional ability. Gundogan is the latest star of Klopp's team, controlling games from midfield with his passing and technical excellence as well as driving the side on with his forward runs from deep. Most encouragingly, aged just 22, there is still time for the Germany international to improve.
Klopp says: "Ilkay has come on leaps and bounds. He has the necessary calm, the eye and the vision. Ilkay now sees bigger spaces, and can also find them with long balls. Furthermore, he is strong on the ball while knowing when to make a tackle."
Hazard joined Chelsea to much fanfare in the summer of 2012 following a high-profile transfer from Lille, where he had been named Ligue 1 player of the year. The young Belgium international responded with a hugely effective debut campaign in which he netted 13 goals in all competition and produced 11 assists in the Premier League - a tally only bettered by Chelsea team-mate Juan Mata. Right-footed but operating chiefly from the left, Hazard is expected to continue his development under the tutelage of Mourinho.
Mourinho says: I'm trying to adapt Eden into everything I think a top player should have. He is a top talent, but it's one thing being a top talent and another being a top player. And I want him to be a top player."
Draxler had his pick of Europe's top clubs in the summer as excitement grew regarding the potential of the 20-year-old German. But after a season in which he netted 10 Bundesliga goals from an attacking midfield role, the Germany international elected to stay at Schalke for their Champions League campaign. With brilliant dribbling ability and a powerful shot in his armoury, Draxler is still expected to move on in search of greater challenges before long.
Keller says: "His decision to stay means a lot to the club. He is one of Europe's most sought-after talents."
Knockout stage perennials they may be, but it has been a long time since Arsenal have really looked in any danger of winning the Champions League. Eliminated at the last 16 stage for each of the last three seasons, just getting there appeared tricky once the Gunners were drawn against Dortmund, Napoli and Marseille. But two wins from two games has added to the new-found optimism in north London and the first of back-to-back games against BVB represents a chance to seriously dent the hopes of last season's finalists.
After struggling in their first Champions League campaign under Klopp, Dortmund went all the way to Wembley last time out but the questionable seeding strategy of UEFA saw them handed a tough draw again. The assignment only got more difficult following defeat to Napoli on matchday one but Marseille were beaten in the second round of games and league form is good. Klopp and his team know they will need to get something from their trip to London or risk finding themselves adrift of the top two at the halfway stage.
The return of Mourinho was supposed to be a guarantee of European efficiency but the 2013 Europa League winners risked a return to that second-tier competition following a home defeat to Basel in their opening fixture. Steaua Bucharest were duly dispatched next time out but six points are likely to be needed from the two games against Schalke for Chelsea to avoid the prospect of travelling to Switzerland on matchday five knowing defeat could spell disaster. It's a crunch clash for them in the Veltins Arena on Tuesday.
A convincing 3-0 win at home to Steaua Bucharest was no great surprise given that the Romanian side are expected to be the whipping boys of Group E. However, Draxler's second-half goal against Basel to secure a 1-0 win in Switzerland could prove more significant. Schalke currently top the group following Chelsea's slip up against the same opposition and a good showing in the forthcoming double-header against the Blues will take Keller's team to the brink of the knockout stages. From there, luck will be needed.
Who will do best in this season's Champions League?