LISBON • It is a problem that has confounded managers and players alike since 2004.
How exactly do you stop a player like Lionel Messi?
Bayern Munich believe they have the solution ahead of today's blockbuster Champions League quarter-final clash with Barcelona in Portugal, but man-marking the Argentinian is not part of their plans.
On limiting the influence of the Barcelona skipper, who possesses the greatest threat to the Bundesliga champions' hopes of a second treble and their sixth European Cup, Germany international Leon Goretzka said: "That can only be done collectively because he is a gifted footballer.
"Thousands of people before me have tried to answer this question. It is nice - after playing against (Juventus' Cristiano) Ronaldo a few times - to play the other formative player of the last decade.
"I don't know how, but we have to force our game on them."
Taking the game to Barca is easier said than done, but if any team can do so, it will be Bayern.
The Bavarian giants have won all 13 games since German football restarted in May following the coronavirus lockdown and underlined their impressive form last Saturday when Robert Lewandowski, the Champions League's top scorer, helped seal a 7-1 aggregate thrashing of Chelsea to book their last-eight berth.
Barca, on the other hand, are staring at their first trophyless season in 12 years unless they can win their sixth European Cup.
While Antoine Griezmann put up a brave front, telling the club's TV channel that "we have the weapons to beat them", the failure to defend their Spanish La Liga title as well as limp exits in the domestic Cups do not lend much confidence to his comments.
Bayern have already won the domestic double and are aiming to emulate Barca in becoming just the second European club to win the treble twice.
Times each Barcelona and Bayern Munich have won the European Cup.
Seven years after their maiden accomplishment and powered by the hot form of Lewandowski - he has already notched a career-best 53 goals in all competitions, including 13 in Europe - Goretzka is feeling confident.
Some critics believe the knockout format of the "Final Eight", which is Uefa's solution to the pandemic, could even out today's game as compared to the usual two-legged ties.
However, it may be more of a detriment to Barca as they cannot rely on the Nou Camp, where they are unbeaten in Europe since 2013, as their safe haven.
And Goretzka revealed Bayern have spent the past few weeks training specifically for an assault on the Champions League. Unlike the rest of their rivals, the German Bundesliga season finished almost a month earlier.
"There is no easy way now. We are here in the sun in Portugal and are preparing for a knockout game in the Champions League," he said. "We're really up for it. Knockout matches are great.
"At the moment, we're playing as a unit, in addition to the quality of the individual players.
"We have a clear plan in hand and our intensity without the ball can make the difference."
Both clubs know each other intimately, with four meetings since 2013 and there will be a reunion of sorts for both Barca's Arturo Vidal and Bayern's Thiago Alcantara, who is a product of Barca's La Masia academy, making today's encounter a likely classic.
On Vidal, who is facing his former side for the first time since leaving the Allianz Arena in 2018, Goretzka said: "He has a first-class mentality with amazing fitness.
"I noticed that during fitness tests - which I took next to him - he can go beyond the pain threshold."
BARCELONA V BAYERN
Singtel TV Ch110 & StarHub Ch214, tomorrow, 2.55am
CHAMPIONS LEAGUE HEAD-TO-HEAD RECORD
2014-15: S-finals, 2nd leg
Bayern 3 Barcelona 2
2014-15: S-finals, 1st leg
Barcelona 3 Bayern 0
2012-13: S-finals, 2nd leg
Barcelona 0 Bayern 3
2012-13: S-finals, 1st leg
Bayern 4 Barcelona 0
2008-09: Q-finals, 2nd leg
Bayern 1 Barcelona 1
2008-09: Q-finals, 1st leg
Barcelona 4 Bayern 0
1998-99: Group stage
Barcelona 1 Bayern 2
1998-99: Group stage
Bayern 1 Barcelona 0