Barcelona - The penultimate UEFA Champions League final disappointment for FC Bayern Munich came in 2010 and, bitter though that defeat to FC Internazionale Milano must have tasted, there's a way for the Bavarians to take something from it - if they've been studying the man who brought their downfall that night in Madrid.
José Mourinho isn't to everyone's taste. However, just as he was crystal clear that night about how he would double-mark Arjen Robben and instruct his Inter players never to let the Dutch winger cut inside onto that vicious left foot which had so damaged Manchester United FC and Olympique Lyonnais that season, so Mourinho has also been the man who most often comes up with the formula to diminish Lionel Messi´s efficacy.
I say 'diminish' because when the 25-year-old Argentinean is at his absolute best then, usually, even the greatest tactical blueprints can be shredded.
But Inter dealt with Barcelona in the semi-final of that 2010 Champions League by a) putting a very tightly-spaced three-man triangle of players in front of an already formidable back four in the away leg and b) playing the ball long, and quickly, at the San Siro. The further the ball was away from Messi as often as possible, the happier and safer Inter were in Milan.
Despite the fact that Barça came within one goal of eliminating Inter, the tactics worked and Messi often looked blocked and frustrated as, crucially, the sequence of tackles he had to slalom through often came within split seconds of one another rather than with even the most minute of thinking or reaction time between them.
Imagine a downhill slalom race. Imagine the great Super G champion Hermann Maier - but the intervals between gates are set at only 15 metres rather than the mandatory minimum 25 metres. Most skiers would fail to make the slalom turns, perhaps even the greatest wouldn't do it either. If you increase speed but decrease reaction time then the chance of success drops too. And that´s when the gates aren't allowed to make a tackle.
That´s the theory which Mourinho patented for Inter at the Camp Nou and has begun to repeat for Madrid in many, if not all, of the 17 Clásico matches since he took over at Madrid that summer.
Messi has often scored, but he´s found it increasingly difficult to impose his trademark dribbling to create the havoc from which he, or a team-mate, converts.
It's well known that Messi likes to drop deep, sometimes as far back as the halfway line, and those who apply that tactic of a little pyramid or triangle of three men blocking his path down the centre of the pitch in front of the penalty box usually don't go with him.
One of Messi´s greatest tricks is to appear static. He'll drop deep, play a couple of listless passes and then just wander forward, oh, say, nine or ten metres at walking pace. But when Barcelona's possession is fizzing quickly from side to side, or within little passing triangles, most teams pay attention to the ball, press those in possession and, hey presto, the ball will arrive at Messi's feet about ten or 15 metres outside the area with more space in front of him and... goal. Usually.
In Mourinho's scheme it´s important that the two or three men who are making a wedge in front of the back four keep their position there for the moment that Messi erupts into a dribble.
Another key factor, quite obvious to a man of Jupp Heynckes' experience and vision is that it's vital not to let Messi establish room on his left foot. Statistics vary across a career but while he's been making himself Barça's all-time top scorer, aged only 25, and placing himself at one successful season away from taking Raúl's all-time Champions League scoring record, around about 80% of Messi's goals have come off his left foot.
Finally, for the defensive-minded in Bayern's set-up it might sound criminally basic but here goes: 'Don't make mistakes'.
Because Messi in full flight is so mesmerising, because he sears himself onto your consciousness it's often ignored how good he is at the little things which give his skills a platform. For example - a pass misplaced by half a metre or less, a rebound, a miscontrol, Messi is onto those like a tiger shark on a seal pup. Sorry for the simile but that's the way it looks from afar. His reaction time is simply unbelievable - predatory doesn´t cover it. Supernatural would be more like it.
So, Bayern, good luck. No player is unstoppable. Messi is also just back from one of the most troubling injuries he's suffered since 2008. But give him a millimetre and he'll take a mile.