Bundesliga
With Barcelona, Inter Milan and Slavia Prague the competition in UEFA Champions League Group F, what do Borussia Dortmund need to watch out for in Europe in the coming months?
bundesliga.com takes a closer look...
How they got there
Dortmund qualified automatically for the group stage of the competition after finishing runners-up behind Bayern Munich in last season's Bundesliga, despite at one stage holding a nine-point advantage at the summit.
Key player
The most exciting young player in world football, Jadon Sancho boasts all the tools to make the Champions League his own in 2019/20. The England sensation has been tying defenders in knots since the start of the season, whilst taking and making chances by the bucket-load. And if he can make mincemeat out of Diego Simeone's notoriously watertight Atletico Madrid as he did in last season's groups, there's no reason why the 19-year-old magician can't run roughshod over the entire playing field - including the Lionel Messi brigade - this time around.
Aims in the competition
To go deep into the knockout rounds - but don't be surprised if they go the distance.
Watch: Find out what makes Jadon Sancho such a threat
Barcelona
Dates Dortmund play them
Tuesday 17 September: Dortmund 0-0 Barcelona (Matchday 1)
Wednesday 27 November: Barcelona vs. Dortmund (Matchday 5)
How they got there
Barcelona defended their La Liga title with room to spare last season, finishing 11 points ahead of runners-up Atletico Madrid and 19 clear of Real Madrid in third.
Key Player
No prizes for guessing who Barcelona's main man is. Messi has been the beating heart of Barca for approaching 15 years; he's the club's record scorer and has been the leading marksman in Europe's top five leagues for the past three years in a row.
Dortmund's path to victory
Three league games in, Barcelona have made their worst ever start to a La Liga season (four points). Either side of coming from behind to beat Real Betis 5-2, Ernesto Valverde's faltering troupe lost 1-0 to Athletic Bilbao, and blew a late lead in their 2-2 draw with Osasuna.
None of those sides have the firepower of Dortmund, though, so if BVB stick to their guns and get the ball to the feet of former Barca striker Paco Alcacer - aka, Mr. Clinical - they could inflict some real damage.
There is, of course, the little matter of stopping Messi. The Argentina ace is yet to play this season because of injury, however, and won't take much comfort from facing the likes of Achraf Hakimi and Mats Hummels if he recovers in time to play in the first leg.
Familiar faces
Barca goalkeeper Marc-Andre ter Stegen came through the Borussia Mönchengladbach ranks, and is Manuel Neuer's deputy for Germany. Midfielder Ivan Rakitic made a name for himself with Schalke, while Arturo Vidal enjoyed stints at Bayer Leverkusen and Bayern.
And let's not forget Ousmane Dembele. The French winger enjoyed an outstanding debut campaign in Germany with Dortmund, scoring six league goals and providing a further 12 assists, before becoming the second-most expensive footballer of all time after completing his summer 2017 transfer to Barca for a fee approximately ten times the amount BVB paid to bring the now 22-year-old to the Bundesliga from Ligue 1 side Rennes 12 months earlier.
Watch: All of Ousmane Dembele's Bundesliga assists in 2016/17
Dates Dortmund play them
Wednesday 23 October: Inter vs. Dortmund (Matchday 3)
Tuesday 5 November: Dortmund vs. Inter (Matchday 4)
How they got there
Inter clinched Serie A's fourth and final Champions League group-stage berth by finishing a point ahead of city rivals AC Milan in 2018/19.
Key player
Inter have since bolstered their ranks, notably bringing in the burly Romelu Lukaku - who has 10 goals in 21 previous Champions League outings - from Manchester United. The Belgium international striker was integral to his country's run to the third-place play-offs at the 2018 FIFA World Cup, but he'll have quite the battle on his hands to avoid becoming the filling in an Akanji-Hummels sandwich.
Dortmund's path to victory
The Dortmund squad have developed a fantastic understanding in their time under coach Lucien Favre. They're set up to keep the ball and attack from all angles, while Inter are still getting to grips with the philosophy of new manager Antonio Conte. Despite the Italian strategist's pedigree, these are early days for the new-look Nerazzurri and they are unlikely to have faced such unrelenting opposition as BVB. The Black-Yellows will create chances - they just need to take them.
Familiar Faces
There are no ex-Dortmund players on the Inter books, but the 2013 finalists will know a thing or two about Valentino Lazaro. The Austrian faced BVB three times in his two-season stint with Hertha Berlin, assisting one goal across two draws and one defeat.
Slavia Prague
Dates Dortmund play them
Wednesday 2 October: Prague vs. Dortmund (Matchday 2)
Tuesday 10 December: Dortmund vs. Prague (Matchday 6)
How they got here
Slavia won the Czech First League in 2018/19, but still had to get past Romania's Cluj in the third round of qualifying - a tie they won 1-0 home and away to reach the groups.
Key player
Josef Husbauer is at the centre of everything for Prague, figuratively and positionally. The Czech Republic international plays in central midfield and can score goals just as well as creating them, but replicating his domestic influence up against Dortmund destroyer Axel Witsel will be easier said than done.
Where they can win
Slavia scored 72 goals and conceded 23 in 30 matches last season, while their nearest challengers, Viktoria Plzen, tallied 47 for and 27 against.
Dortmund hit 81 and shipped 44 in 34 outings against much higher-calibre opposition, and will simply have too much quality for Slavia in all areas of the pitch.