Lionel Messi was at it again on Sunday night.

The Argentine popped up late on to win his side all three points against Atletico.

Messi meant business when he picked up the ball just inside Atletico's half with five minutes remaining.

He drove at goal, played a one-two with Luis Suarez, and then smashed an unstoppable effort into the net from just outside the box.

It was a well worked goal and one that was well worthy of winning the game.

Watch the goal below:

That was his 614th goal for Barcelona. He also has 237 assists for the club. Absolutely ridiculous numbers.

And his performance led to an unlikely source claiming Lionel Messi is the greatest of all time.

Iker Casillas played with Cristiano Ronaldo for six years at Real Madrid.

But the Real Madrid legend showed he was team Messi on Sunday night.

Following the game, Casillas tweeted: "Formula for football: goalkeeper (Ter-Stegen) 🔝 & player (Messi) 🐐".

But that's not the first time Ronaldo's former teammates have sided with Messi over him.

Wayne Rooney played with Ronaldo during their time together at Manchester United but he has said Messi is the greatest player of all-time on numerous occasions.

"I think I've said this before, but they're both probably the best two players to ever play the game," he said last year, per Goal.

"I just think Messi is, in my eyes, the greatest ever."

Ryan Giggs has the same opinion as Rooney.

"Obviously I lean towards Ronaldo a little bit because I played with him and saw him develop as a player," he said last month, per the Sun.

"But Messi is a genius, he's a once in a lifetime player. It's as simple as that."

And Real Madrid legend Raul also picked Messi over Ronaldo.

"I was lucky enough to play with Zidane, Ronaldo, Figo, Cristiano... but Messi is different," he told Sports Illustrated in 2015, per FourFourTwo.

"He makes everything look so easy, so effortless – even the impossible. When you watch him play, it's almost as though you are watching him in the street playing with his mates."

Paul Scholes has also repeated that he thinks Messi is better than Ronaldo.

When asked to pick between the two last year, Scholes said, per the Mirror: "Messi. But Ronaldo is brilliant.

"Ronaldo is sensational at what he does, with pace and power. He scores, he takes free-kicks.

"But as an all-round footballer, Messi - wow, his passing - has absolutely everything."

Casillas is the latest former teammate of Ronaldo to side with Messi... and he surely won't be the last.