It's been four long years for Bayern Munich.
Four years for Germany's finest to plot how to erase the memories of that painful one-sided 2009 Champions League quarterfinal defeat to the illustrious opponents they finally get to re-engage on Tuesday evening: FC Barcelona.
Back on April 9, 2009, Munich's finest were torn to shreds by a classy first-half display from the all-conquering Catalans, who would go on to lift the famous "cup with the big ears" in Rome on the way to an unprecedented sextuple.
The stunning architectural masterpiece that is the Allianz Arena will provide the perfect backdrop for the first leg of what is sure to be one of the great Semi Final matchups of this, or any other edition of the UEFA Champions League.
Both clubs have been dominant forces in Europe's premier club competition recently with either Barca or Bayern in the final in each of the last four seasons.
Cules are desperate to see their beloved Blaugrana rekindle a love affair with Wembley Stadium as they bid to become the first side to record a unique treble of Champions League Final wins at the same venue.
Bayern have enjoyed a terrific season domestically and in Europe with only three defeats to their name in all competitions. Bayer Leverkusen took all three points back in October during their Bundesliga clash, and perhaps more surprisingly both Bate Borisov and Arsenal defeated the German giants in the Champions League.
With 127 goals in all competitions, including six this past weekend, Bayern have been an attacking force par excellence and with Barcelona being particularly generous in defence, the Catalans are going to have their work cut out to impose their own natural pressing game.
So let's take a look at how Barcelona should set up in order to keep Bayern at bay...
Puyol's influence alongside Gerard Pique at the heart of the defence is well documented and it would be tempting to bring the old war horse back in to provide some stability.
However, after five weeks out and knee surgery, the last thing that the club and player need is for him to be rushed back, susceptible to further injuries. The player has an outside chance of making the Second Leg of this Semi Final and depending on the result from Munich, there may well be a clamour for his inclusion.
In his and Javier Mascherano's absence, Tito Vilanova has a choice of partnering Gerard Pique with either Marc Bartra, Alex Song, Adriano or the incomparable Eric Abidal at centre back.
Song has looked a little lightweight when in a central defensive role and against such a potent attacking threat, the Cameroonian is likely to be found wanting. His lack of pace will almost certainly be highlighted in this game.
Adriano has played in the position before and has generally acquitted himself reasonably well, however I'm loathe to include him here precisely on the basis that it's not his natural position.
As we saw with Martin Montoya against Levante, playing out of position for the benefit of the team is acceptable and often required, however in a match as significant as this one, Barcelona cannot afford to weaken their defensive capabilities.
Abidal was imperious against Levante. His calm and assured presence has certainly put the cat amongst the pigeons. While I expect the Frenchman to be in the squad, I don't see Tito starting him. It's too early in his recovery to expect him to be Barca's defensive saviour.
Which leaves Marc Bartra as the only other natural centre back that Barca have fully fit and available. Despite only a handful of appearances in three years (which tell you that manager Tito Vilanova is unsure that the youngster is the long term answer), I would have no hesitation in starting with Bartra for the reasons stated above.
Many will point to Bartra's lack of experience as reason enough not to include him but I believe the exceptional set of circumstances Barcelona find themselves in leave them little choice.
Bayern's influential Toni Kroos is out for the season and in form forward Mario Mandzukic is ruled out of the first leg after receiving a booking in Bayern's last Champions League match v Juventus.
Kroos' tireless work rate (as evidenced by the heat map below) and understanding with the rest of Bayern's attacking quartet will be sorely missed. Whilst Mandzukic has enjoyed an exceptional season, his absence paves the way for the return up front of Mario Gomez.
Prolific last season with 41 goals, the effervescent, powerful and direct Gomez is a real handful, as his recent six-minute hat trick against VfL Wolfsburg proved.
Equally adept at the ball into feet or controlling the high ball into the box, Gomez will feed off of through balls played on the deck by Bastian Schweinstiger or Thomas Mueller, or crosses from wide areas from the likes of Ribery and Robben.
I'm not sure that Bartra has the necessary presence to out-muscle Gomez, so this duty will fall largely to Pique who will need to stick close to the German all game rather than marking the areas around him, and in so-doing allowing him time on the ball.
A disciplined performance from the centre back is a must as Bayern have more than enough about them to exploit Pique's wanderlust.
Mueller will support Gomez by drifting into any spaces created so Sergio Busquet's role just in front of the back four will be as important as ever.
He will be charged with not only marshalling Mueller, but providing further cover behnd Xavi and Iniesta should Schweinstiger break through the midfield areas.
Pique's central defensive sidekick will need to ensure that the gap between them is minimal at all times and be quick off the mark when necessary if Mueller and/or Schweinstiger evade Busquets.
Bartra certainly has the pace to close down that space quickly and effectively and force Mueller et al into less dangerous territory.
The conundrum facing Busquets will be whether to support Xavi and Iniesta when pushing forward as a midfield unit. Given the often devastating threat Bayern pose on the break, he must be mindful of his defensive responsibilities which he often carries out with great aplomb.
However, in so doing, he then runs the risk of allowing Barca to be outnumbered through the central areas as they move higher up the pitch in an attacking sense, should Mueller drop back to help out.
I would expect Lionel Messi to stay in quite an advanced role. By tucking in behind Javi Martinez and Schweinstiger, rather than dropping deeper, he will not only draw out van Buyten and Dante toward him, but also tempt the defensive Martinez and/or the more attack-minded Schweinstiger to drop back, thus opening up the space for the supporting combo of Xavi and Iniesta.
If worked correctly, anyone of the three (Messi/Xavi/Iniesta) will then have the time and space to play the pass inside the full backs for Barca's wide players to run onto.
Bayern's dual threat of Robben/Lahm on the right hand side and Ribery/Alaba on the left will be constant. Both Jordi Alba and especially Dani Alves must take care not to move across too much when play is on the opposite side to them.
This part of Alves' game was never better illustrated than during the 2-3 defeat against Real Sociedad. Chori Castro's goals were as a direct result of Alves (circled) ending up almost next to Carles Puyol and therefore neglecting his role as right back.
It created an astonishing amount of space at the back post and Jupp Heynckes will have identified this area as a particularly weak link in Barca's armoury.
When faced with their direct opponent, the Barca fullbacks will be better served in showing the attackers down the outside. In escorting Ribery/Robben out wide, both Alves and Alba have the turn of pace necessary to curtail any threat and stop crosses reigning in from those wide positions.
I expect much of Bayern's thrust will come via Robben down the Bayern right hand side but Robben is easily and quickly frustrated if things are not going well for him.
With the propensity he has for simulation, Barcelona will be mindful of allowing Robben to turn back into those central areas where can be most dangerous and most theatrical.
Cristian Tello, whom I believe is working his way to a regular slot on the left side of a Barca front three, is my choice for keeping Phillip Lahm quiet. The defender will be looking to support the attack at every opportunity and cutting off the supply line to Robben will be essential.
Tello offers a particular threat down that side of the pitch (which neither Villa or Sanchez do) and this should stymie Lahm's forward movement. If Van Buyten should move over to "double up", this will only open up space for Lionel Messi to work in the most dangerous area of the pitch.
If Schweinstiger were to drop deeper to restrict Tello's incisive movement, then this potentially then frees up Andres Iniesta to wreak havoc.
The process is repeated on the opposite side of the pitch. I'm placing Pedro there for the same reasons as Tello on the opposite wing. Pace, work-rate and in the young Spaniard's case, a knack for scoring important goals in the big matches.
Pedro should also be able to keep Alaba's forays to a minimum with intelligent use of the space around him. If Dante is to replicate his fellow defender Van Buyten's movement, he's aware that Messi is lurking and Martinez already has Xavi to contend with so he will be loathe to leave his central midfield sentry.
After a quite disastrous performance against Levante, which may well have knocked the players' confidence, Vilanova may opt to leave Cristian Tello on the bench and use him as an impact sub if required.
Should he do so, he will then need to choose between the hard-working Chilean, Sanchez, or the more experienced Villa.
It's key for Barca to recycle quickly wherever on the pitch the ball is won. The Blaugrana need to impose their passing game (as in the match vs. AC Milan) to ensure the Germans are kept on the back foot.
If Barca are to play their usual high defensive line when pressing forward, then I would prefer that Bartra stays slightly further back than Pique and can therefore use his pace to counter any threat over the top.
The high ball into the area has always been Barca's achilles heel and highlights their urgent need for a commanding centre back in the Puyol mode.
There are chess games to be won all over the pitch but I believe that Barca have every chance in this match, as long as they are disciplined, defend from the front and hunt in packs to win back any lost balls.
With home advantage, Bayern will be favourites going into this game, but Tito Vilanova will be quietly confident of taking a positive result back to Catalonia.