Carlo Ancelotti believes it is impossible to stop Lionel Messi if the Barcelona superstar is fully fit.
Messi regained the Ballon d'Or from Cristiano Ronaldo in January and has scored 35 goals this season as Barca remain on course to make history by winning back-to-back trebles.
And former Real Madrid coach Ancelotti has lifted the lid on what it is like to try to prevent the magical Argentinian from influencing games.
"Man-marking Messi is very complicated. The defender marking him would have to be at a very high level," the Italian wrote in his column for Sina Sports.
"The best way to stop him is by defending as a team, keeping the space between the lines tight and now allowing him to touch the ball. You need a lot of players in midfield to make that happen. That reduces Messi's options and he will see less of the ball, at least in dangerous positions.
"We know that he likes to cut in from the wing and get the ball onto his left foot. But the problem is that Barcelona have more weapons than just Messi. If you focus on Messi, their other attackers can do the damage.
"But if Messi is at 100 per cent physically, it is impossible to try to stop him, no matter who the coach is and what his strategy is. His enormous talent makes it nearly impossible to anticipate what he will do, so there is no way to keep him quiet."