"He watches my legs," Jan Oblak tells Sky Sports. "If I make one step, he will see it and shoot to the other side. This is why he is the best. This is why he is so difficult. He does not show it but he is always looking. He is always watching you. His eyes are on the ball but he sees you.
"He sees everything, I think."
Oblak, perhaps the best goalkeeper in the world, is in the comfort of his Madrid apartment describing in detail the challenge of facing Lionel Messi, perhaps the best footballer there has ever been. There are times when it is as if he is describing the bogeyman himself.
The Atletico Madrid goalkeeper is speaking not long after his team's 1-0 win over Barcelona, their first against Messi and the rest in La Liga for over a decade. Oblak won that one but there have too many defeats, too many late Messi goals, for him to be anything other than humble. "He is still the best player in the world," he insists.
In all competitions, there have been three clean sheets, including a 2-0 win in a Champions League quarter-final. "For sure, that was my best memory against him." But that was one game among 17. 10 of them have seen a Messi shot find its way beyond Oblak.
"He has scored many goals against me. Too many! But he is a great player, an amazing player, the best player. There are many times that he scores a goal and you have this feeling that you cannot understand how he has scored so easily. You are not even close. Sometimes it feels like he has just passed the ball into the goal, it is not even a shot."
Oblak is honouring Messi's achievement, completed against Valladolid on Tuesday, of scoring 644 goals for one club, breaking the record set by Pele with Santos. Budweiser are marking the historic moment with 644 specially created bottles, individually numbered to represent each goal, and recognising the role that every single one of them has played in pushing Messi towards greatness.
A little reluctantly, Oblak has had to claim responsibility for 10 of them. "It is always difficult to talk about because goalkeepers do not like conceding goals." But it is revealing.
So much has been written about Messi over the years but little of it from the perspective of the victim. The goalkeeper. The last line of defence. The man out to stop him.
Oblak's insight suggests that the contest between the two is tactical and technical, physical and mental. An examination of mind and body that requires concentration at all times.
Nothing illustrates this as clearly as Messi's record of having scored an 86th-minute goal against Atletico on three different occasions. Just when the job is almost done, it isn't.
"It is strange," says Oblak. "Sometimes you think you are controlling them, you are controlling him. But in a second, he changes the game, he scores a goal, and Barcelona win.
"Sometimes you do not see him. Maybe you are thinking it is not dangerous. And then he scores. This happened to us last season. You need to be 100 per cent concentrated."
The tactics against Messi
Diego Simeone demands that concentration from his players and certainly from the man who he has described as the Messi of goalkeeping. "If your coach says that it can only means good things," says Oblak. But does the Atletico boss have specific plans for Messi?
Oblak argues that there is only so much that can be done.
"Normally, goalkeepers, we are shouting all the time to help the defenders but I know it is difficult when Messi is on the other side. The defenders do their best but it is difficult to do anything tactically to stop Messi because you never know what he is going to do.
"All you can do is play hard and when you see him don't leave him. Try to steal the ball but don't give a foul close to the goal because he is great at free-kicks. He is great at everything.
"If you are too close he will go past you. If you are too far he will shoot. It is not easy to decide how you will defend against him because of his unpredictability. It is impossible."
Where does Messi shoot?
Oblak returns time and again to this issue of unpredictability and with good reason. The stats suggest Messi puts the ball either side of the goalkeeper with almost equal regularity.
His trademark finish is to the goalkeeper's right - the one that Oblak refers to as a pass - but any attempt to anticipate such a strike will be punished with a whipped finish into the opposite corner, as he famously did in the final of the 2015 Copa del Rey against Athletic.
"That is the problem of Messi for goalkeepers," says Oblak.
"Anticipation depends on the player because there are some players who you can easily predict. There are some players who it is more difficult to predict. Then there is Messi. He is impossible to predict. Not many players have the possibilities that he has on the ball.
"You can never predict where he is going to shoot and you can never predict when he is going to shoot. When it comes to Messi, you can never predict anything. Ever."
When does Messi shoot?
This issue of when Messi will shoot is an added complication. Goalkeepers must be prepared for the early shot that might catch them unawares but they must also appreciate that he is capable of delaying the shot or even threading a pass through for someone else.
"Many times, this is a problem against him. Maybe two or three defenders will go towards him to steal the ball from him but then he will pass to another player and they score.
"You are not just waiting for the shot, you are waiting for the pass. You are waiting for all kinds of things. Will he shoot? Will he pass? Will he dribble? I repeat, it is impossible."
One-on-one with Messi
Sometimes, when the defence has been breached and all else has failed, the shot is inevitable. One-on-one against Messi is the worst case scenario for the goalkeeper.
Oblak found himself in that situation during the first half of Atletico's recent win over Barcelona, albeit from a narrow angle, and managed to keep out the shot. He has a strategy.
"If you go down, he will chip you," he explains. "If you stand up, he will go through your legs. If you go right, he will shoot left. If you go left, he will shoot right. But, in one-on-one situations, the most important thing is to wait until the last second.
"Do not speed things up. You need to watch the ball and to wait."
Wait, and hope that Messi makes a mistake?
"Then, you need a lot of luck."
Mental challenge of Messi
Acceptance that Messi cannot always be controlled might seem like an admission of defeat but it is an important psychological tool for a goalkeeper. The ball is in the net and there was nothing that could be done. Deal with it and move on. Control the controllables.
"When you play against the best, you know you are going to have to be at your best to stop them," adds Oblak. "But you also know that when such a good player is playing against you there is always the possibility that he will score. If he does what he can do, it is impossible.
"If he has his day, if he is in great shape, it really does not matter if you are at 100 per cent. His talent is too much.
"Most of the time, you must accept it is going to depend on him."
What is Messi's future?
This latest record-breaking feat comes at a time when Messi's form has been under greater scrutiny than ever before. At the age of 33, those questions are likely to form a constant backdrop now. But Messi has the backing of a certain Slovenian, his long-time opponent.
"Some good players from Barcelona went out, some new players came in," says Oblak. "It is not easy for them, it is not easy for him. But he will show that he is still the best, I am sure. Even if he does not play so good in one or two games, at any moment he could show again that he is the best. He has been showing that every season for the past 15 years.
"Barcelona should be very pleased he is there. He has shown this with the titles that he has won and how many goals he has scored. Barcelona without Messi are totally different."
Football without Messi would be totally different too.
"I am sure that he is going to score many more than just 644, even though it is already a lot," he adds. "It is a really special achievement. I can only say the best words about him because he is the best. He has shown it for so many years and I can only congratulate him, wish him all the best, and hope that he scores many more goals.
"Just not against me."
Jan Oblak spoke as a LaLiga ambassador, as part of Budweiser's celebration of Lionel Messi's record breaking 644th goal. For more info visit youtube.com/Budweiser