The Argentine allowed him to kick it and Neymar couldn't score
One of the surprises during match against Villarreal was that Leo Messi allowed Neymar to kick a penalty when they were winning 3-1. But the Brazilian couldn't score because the goalkeeper Asenjo cleared the ball. The goal would have meant a good result to face second leg more comfortably.
In this video you can see how Leo Messi reacted after Neymar missed the penalty. The Argentine regrets and tries to continue the play.
This gesture was important, as last time Messi allowed another player to kick a penalty was in 2009/10 season in Zaragoza, where he let Ibrahimovic kick. Messi had scored 3 goals and Ibra scored. "He needed the goal," said Messi.