Jurgen Klopp will return to Signal Iduna Park for the first time since leaving last summer when he takes his Liverpool side to face Borussia Dortmund in the first leg of their Europa League quarter-final on Thursday evening.
The German oversaw 319 matches in charge of the Bundesliga outfit, steering them to two league titles, a domestic cup and the final of the Champions League before his departure at the end of the 2014-15 campaign.
Borussia Dortmund
The home fans are expected to give a rapturous reception to Klopp when he steps out at the Westfalenstadion, having seen him transform their club back into a European force during his time in charge.
His final season at the club may not have gone to plan, rescuing a seventh-place finish following a dreadful start to the campaign and losing the DFB-Pokal final in his last game in charge, but he is still warmly remembered in Dortmund.
That is not to say that they will do him any favours on Thursday evening, though, as they look to justify their tag of tournament favourites once again.
They are certainly the form team left in Europe's secondary competition having not lost a single game since their return from the winter break - a run of 16 matches that includes 14 victories.
Indeed, the only team to prevent Dortmund from winning a match in their last 12 outings is Bayern Munich, who were forced to settle for a goalless draw in the league as their battle at the top continued.
Dortmund have an uphill struggle if they are to bridge the five-point gap to Bayern over the final six games of the Bundesliga season, but it is very much a two-horse race, with third-placed Hertha Berlin a full 19 points behind.
Dortmund will face Hertha in the semi-finals of the DFB-Pokal, with Thomas Tuchel so far doing an admirable job of stepping into Klopp's shoes and pushing for silverware on all fronts this season.
Their Europa League campaign continued in style in the last round when they cruised past Premier League title-chasers Tottenham Hotspur 5-1 on aggregate, winning both legs just as they had done against Porto in the round of 32.
Their passage to this stage of the competition has not been as easy as they have made it look in the knockout rounds, but they made hard work of getting out of their group, finishing second behind Krasnodar having lost to both the Russian outfit and PAOK.
That defeat to the Greeks is their only home loss of the season in any competition, though, and including the tail end of last season that makes it just one defeat in their last 27 matches in front of their own fans - a run they kept alive with a 3-2 win over Werder Bremen at the weekend courtesy of two goals in the final 13 minutes.
Once again, Bayern Munich are the only visiting team to have avoided defeat at the Westfalenstadion in the last nine matches - one of only three games that Dortmund have failed to win there during that 27-match streak.
Few know the stadium and the effect it can have on the hosts better than Klopp, though, and he will be ensuring that his new side are in no doubt as to what they are up against on Thursday.
Recent form: LLWWWW
Recent form (all competitions): DWWWWW
Liverpool
Klopp is not exactly a reserved man at the best of times, but it is sure to be an extra-emotional occasion for him when he returns to the club where he became a household name.
It will be all eyes on the 48-year-old right up until kickoff, but he will be the last person who needs telling that matters on the field will determine whether it is a joyous return or a miserable one.
The odds are stacked against his side, but they have shown on a number of occasions this season that they are capable of rising to the big occasion, and if anyone can bring down the favourites, then it makes sense that their former boss, who developed such a bond with his players during his time at the club, would be the man to do it.
There is always a question mark over Liverpool at the moment, though, with inconsistency plaguing their season and leaving a top-four finish now seemingly out of their reach.
The gap to fourth-placed Manchester City is currently nine points, and while the Reds do have at least one game in hand over the teams above them in the table, both Manchester United and West Ham United look better placed to cash in on any City slip-ups in the closing stages of the season.
It may have been different had they been able to hold on to leads in their last two outings, but having blown a two-goal advantage in the final half-hour against Southampton before the international break, they were pegged back by Spurs in a 1-1 draw at Anfield on Saturday.
A draw with Tottenham this season is by no means a poor result, but it saw them slip further behind in the top-four race and their best hope of playing Champions League football next season now appears to be qualification by winning the Europa League.
They could not have picked an opponent that they would rather beat in the last round than Manchester United, whom they overcame 3-1 on aggregate in the first ever European meeting between the two most successful sides in English football history.
A 1-1 draw in the second leg at Old Trafford was enough to progress and maintain their unbeaten record in this season's competition, although six of their ten matches have ended as draws.
There will be no complaints if they take another draw back to Anfield next week, but hopes of anything more may be slim having only won five of their last 15 away games in all competitions and just one of their last seven in the Europa League.
Despite their impressive European pedigree, this is the first time that they have reached the quarter-finals of a UEFA competition since the 2009-10 season, and Klopp will need to pull off an upset against his former employers if he is to take them any further.
Recent form: WDDWWD
Recent form (all competitions): WWDLD
Team News
Liverpool could be boosted by the return of Brazilian playmaker Roberto Firmino for this match after he travelled with the squad to Dortmund despite concerns over a hamstring problem.
Christian Benteke is not expected to feature, though, and the match could also come too soon for Lucas Leiva, who has been sidelined since the League Cup final in February.
Martin Skrtel may be hopeful of a recall, but Klopp could instead name an unchanged side to the one that drew with Spurs on Saturday.
Dortmund, meanwhile, are expected to bring skipper Mats Hummels back into the starting XI after he was rested at the weekend, although Neven Subotic is still sidelined due to thrombosis in his arm.
Ilkay Gundogan returned to training on Tuesday following almost a month out with a foot injury, but Tuchel may opt to start the midfielder on the bench rather than throwing him straight back in.
Patrick-Emerick Aubameyang has 36 goals to his name in all competitions already this season, ten of which have come in the Europa League.
Borussia Dortmund possible starting lineup:
Burki; Piszczek, Ginter, Hummels, Schmelzer; Weigl, Castro, Durm, Mkhitaryan, Reus; Aubameyang
Liverpool possible starting lineup:
Mignolet; Clyne, Lovren, Sakho, Moreno; Henderson, Can, Milner, Lallana, Coutinho; Sturridge
Head To Head
These two sides have met three times in European competition before, with the record evenly split at one win apiece and a draw so far.
The most notable meeting between the two sides was in the 1966 European Cup Winners' Cup final, when Bill Shankly's Liverpool were beaten 2-1 in Glasgow. They also met twice in the 2001-02 Champions League group stages, with Liverpool drawing 0-0 in Dortmund before a 2-0 win at Anfield.
Dortmund have only ever lost one of their ten previous home matches against English opposition, while overall their record stands at 11 wins, four draws and six defeats from 21 competitives meetings. Liverpool, meanwhile, have won 16 of their 34 games against German opposition, but only two of their 15 meetings on German soil, drawing eight and losing five.
We say: Dortmund 2-1 Liverpool
Dortmund are in such good form coming into this match that it is hard to see past a home victory. However, Klopp may have a few tricks up his sleeve against his former club, and if Liverpool are able to play their high-pressing game then it could cause the hosts some problems. We feel that Dortmund will come away with the win, but one that keeps Liverpool right in the tie.
