After a fantastic first half, which ended 2-1 to Barcelona, the visitors came out after the break looking to finish the game and not to have a repeat of what happened against Huesca.
Although Athletic had quite a few dangerous chances, Koeman's men quickly regained control, and Messi started to appear fluently.
The Argentine hit the bar with a spectacular hit which deserved to have been the third.
It didn't come in that passage of play, but it did in the following. Griezmann set up the Argentine and Leo hit it off the bar and in to make it 3-1 Barca.