The result has Barca on the brink of being confirmed champions.
"It was a great play by Sergi Roberto, which Luis left perfectly for me," Aleña said.
"I'm happy to have been able to help the team pick up three important points, but the goal was thanks to Luis Suarez. He's a crack, the best No.9 in the world. He saw my run and left [the ball] for me to score."
The midfielder also revealed that coach Ernesto Valverde told him to "get forward and support the forwards and break into the space".