His (second) goal was also his 500th and he's playing for an incredible club.
"He is the best player for me in history and I have seen a lot of football", said Barca boss Luis Enrique as he celebrated victory in his final Clasico in charge. "It is something that is normally more a characteristic of our rivals, but we like to do it too", added Enrique.
Sergio Ramos had also been sent off for a wild challenge earlier in the second half.
Real Madrid have stripped over 350 fans of their season tickets after a conspicuous number of Barcelona supporters were spotted watching El Clasico from sections of the Bernabeu supposedly reserved for home fans.
Casemiro went into the book for a foul on Messi in the 12th minute as Barcelona's all-time top scorer frequently dropped into midfield to help the team develop moves. It's time to enjoy the best player in the world and of all time. "It went as we'd hoped".
And captain Iniesta admits he's still surprised by his team-mate.
Messi had not scored in the Clasico in three years but he more than made up for the goal-drought in this encounter and lead his team to victory. "For us, it is an honour and a blessing for the club".
"We have achieved our objective, we have a chance and we have to take it".
Coach Zinedine Zidane insisted that, while they might now sit second, the fact that Madrid have played one game fewer means they still control their own destiny. When you don't kill off the game, it can pass you by and that's what happened. However, Real Madrid still have a crucial game in hand where they can again surge to the top of the points table. "There is a lot of the league left and we have to think about the next game".
He scored twice, but Barca aren't just Messi.
"I can not be happy", Zidane told reporters after his first loss in three Clasicos.
They may play together at the back for Spain, but the war of words between Sergio Ramos and Gerard Pique basically never stops.