Argentina star Messi has missed four penalties for club and country this season, but he is determined to improve.
"Yes there is a lot of frustration that I have missed a lot of penalties, both for the club and for Argentina," Messi told Barca's official magazine. "I am the designated penalty taker, but when the goalkeepers study you they know your ideas more.
"It is true to say that a well taken penalty is very difficult to stop, but now it's more complicated when it comes to taking a penalty.
"These are things in football, but it's true that I have made poor decisions, such as against Manchester City, when the goal would have given us a very important advantage.
"[But] like everything in football, we are fortunate that every three days there is another game, you cannot keep regretting what happened."
