Without looking back to the stands, Alves picked up the banana and ate it before his kick.
Barcelona won the game 3-2. In a sly rebuke to the Villarreal fan, Alves said later that the banana gave him the nutrients he needed to win.
"I don't know who it was, but thanks to whoever threw the banana, the potassium gave me the energy for the two crosses which led to a goal," he told reporters.
Barcelona teammate Neymar lent his support to Alves afterward on Instagram.