Rarely has one man been the focus of such attention in the Europa League.
But Juergen Klopp's return to Borussia Dortmund as Liverpool manager for the first leg of the quarterfinals was always going to be an emotional affair with such a strong bond between him and his former club after seven largely successful years.
Klopp oversaw steady progression after taking over Dortmund in 2008 and led the young side to back-to-back Bundesliga titles by 2012, when the club claimed its first double by humbling Bayern Munich in the German Cup final. A Champions League final appearance in 2013 was as good as it got after that.
The end, when it came in 2015, was mourned by Dortmund fans who remembered only the good times, as well as Klopp's infectious good humor and enthusiasm.
''Danke Kloppo'' (Thank you Kloppo) was trending on Twitter at the time.
Klopp is already extremely popular among Liverpool fans and players for much the same reasons, with his passion for the game and his new club clear to all from his behavior on the touchline and in news conferences.
Klopp quickly put his stamp on Liverpool through the team's high-energy approach and fierce pressing game. Results have generally been inconsistent but are starting to improve, like they did at Dortmund, and Anfield has become something of a fortress. Fans appear happy to give him time to build his own team.
It's widely felt that Liverpool will be a force under Klopp, especially once he gets his own players in, and that the pair are a perfect fit - just like it was at Dortmund.
Here are some things to know about Thursday's matches:
Of course Liverpool's trip to Germany isn't just about Klopp - even if German broadcaster Sport1 was reportedly planning a ''Kloppo Cam'' focused only on the Liverpool manager for the duration of the game.
For Dortmund, the Europa League represents arguably a better chance of silverware than the Bundesliga, where it trails Bayern by five points despite producing the best-ever campaign by a second-place team.
Dortmund also has a German Cup semifinal match to come against Hertha Berlin, but progression in Europe is a priority.
Ilkay Gundogan, Sokratis Papastathopoulos and Mats Hummels took part in Tuesday's training session and look set to return, leaving Neven Subotic the only player on Tuchel's injury list.
Liverpool playmaker Roberto Firmino looks set to miss out with a hamstring injury.
Fernando Llorente returns home to face the player who took his place in the hearts of Athletic Bilbao's supporters.
Llorente joined Sevilla this season from Juventus, but the Spanish striker grew up playing for Bilbao from 2005-13 before heading to Italy.
''I spent 17 wonderful years of my life in Bilbao,'' Llorente said. ''It was always an honor to play for them. Now it is my turn to play against them, and I will give everything for the Sevilla shirt. It will certainly be a very hard match.''
Bilbao is now led by veteran striker Aritz Aduriz, who recently got a call-up for Spain based on his excellent scoring form since taking over for Llorente.
The 35-year-old Aduriz leads the Europa League this season with eight goals, making Bilbao the competition's top-scoring team with 20 goals in 10 matches.
Two-time defending champion Sevilla has struggled on the road this season and has yet to win away from home in five European matches.
With a berth in next season's Champions League just about assured, Villarreal can now focus on winning an elusive title.
A 2-1 win at Eibar on Sunday gave Villarreal control of fourth place in the Spanish league with an eight-point cushion over fifth-place Celta Vigo.
Villarreal has twice reached the semifinals of the Europa League, to go with one semifinal appearance in the Champions League, and is aiming for another shot to add to its InterToto trophy from 2003.
Playing some of the most attractive passing football in Spain, Villarreal is anchored by midfielder Bruno Soriano. At Eibar, the captain played his 364th match for Villarreal, surpassing Marcos Senna's club record of 363.
''The most important thing now is to achieve all the exciting goals we have this season,'' Soriano said.
Villarreal hasn't conceded a goal while winning all five of its home matches in Europe this season.
Sparta, meanwhile, is undefeated in 12 Europa League matches and has won its last three away matches in the tournament.
Braga, the only Portuguese club with a chance to win four competitions, is unbeaten in five European home matches this season.
The northern Portuguese club still has a chance to win titles in the Europa League, Portuguese Cup and the Portuguese League Cup, as well as lying fourth in the domestic championship
Shakhtar has yet to lose in this season's Europa League.
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