Porto coach Lopetegui's prized possession

FC Porto coach Julen Lopetegui tells Champions Matchday why keeping the ball matters so much in the UEFA Champions League.

"While we have the ball, we have the chance to attack and the opposition cannot attack us. If you have it, the problem is how you use it, where you have it and why you have it. These are the questions coaches always try to answer and improve on.

"Evidently, the more possession you have, the more chances you have to win the game. But there are no mathematics in football. You have to be aggressive in possession and mix up your attacking style, with different attacking options against different opposition.

"Should you adapt to the opposition? No. What you have to try to do is look to answer the questions that the opposition asks you by attacking and taking the initiative. That isn't the same as adapting your game to the opposition. Neutralising the threat posed by the opposition isn't adapting your game to theirs, it's about trying to gain an advantage from your own team's ability and quality while also knowing how to reduce the threat caused by the opposition."

Porto players in training©Getty Images

The theory of evolution
"One thing about football nowadays is that you have less time and space on the ball. The tactical and physical evolution of the game means players have less time to decide on their next move, to pick up the ball, turn and play. Players are therefore forced to play a quicker and more precise game.

"It makes the players better. It isn't a sport you can measure in seconds or metres like many other sports. The evolution of football is about the increased difficulty of performing well, creating space and acting quickly. That is what teams are trying to battle against.

"It can be negative if you have possession but don't know how to make the most of it. In theory, if one team has 100% possession, they can't concede a goal. You want to have the ball as much as possible, not just for the sake of having it, but in order to win games."

Balance of play
"You have to look for a balance based on the players you have. You try to make the players adapt to a certain style of play, and you also try to adapt that style to the players at your disposal. Finding that balance is often about teamwork; both sides must complement the other well. That's the important part.

"One of the characteristics of football is that you need to be capable of winning, playing well and being competitive by employing different styles. Each team plays differently. That's one of the big secrets in football. In theory, if you keep the ball for an entire match, you can't concede a goal. In reality, a team with 20% possession can still beat you."

Champions Matchday is the official magazine of the UEFA Champions League and is available in print or free to download in digital format. You can follow the magazine on Twitter @ChampionsMag.