June 3, 1997. Lyon, France. A friendly match that basically meant nothing on paper. But then, a bald Brazilian left-back with thighs the size of tree trunks decided to take a free kick from roughly 35 meters out.
The free kick Roberto Carlos scored that night didn't just beat Fabien Barthez. It broke the internet before the internet was a thing. You've seen the clip. A 100-foot run-up, a violent strike with the outside of the left boot, and a ball that headed so far right it nearly hit a ball boy. Then, like some sort of glitch in the Matrix, it boomeranged back into the net.
Honestly, it looked like a mistake. Even Carlos thought so.
The Magnus Effect on Steroids
Most people talk about the "banana shot" as if it’s just a cool trick. But for physicists, this specific free kick Roberto Carlos delivered became a career-defining case study.
Basically, it's all about the Magnus Effect. When a ball spins, it creates a whirlpool of air around itself. On one side, the air moves with the spin (low pressure); on the other, it moves against it (high pressure). That pressure difference sucks the ball toward the low-pressure side.
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But here’s the kicker: Carlos didn't just kick it. He murdered it.
The ball was clocked at around 137 km/h. At that speed, the air around the ball is turbulent. It’s chaotic. As the ball travels and eventually slows down, the airflow transitions from turbulent to laminar (smooth). That transition is exactly when the "miracle" happens. The drag coefficient drops, and the spin suddenly takes over with way more force than it had at the start of the flight.
That’s why the ball stayed straight for so long before making that sharp, disgusting turn at the last second. It wasn't a constant curve. It was a late-breaking snap.
What Most People Get Wrong About the Technique
You’ll hear "experts" say he used the outside of his boot. That's sorta true, but it's not the whole story.
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Carlos himself has explained that he hits the ball on the valve. Why? Because the valve is the heaviest, hardest part of the ball. It gives the strike more "pop." He didn't just swipe across the ball; he hit it with a "jolt."
- The Run-up: He started almost at the center circle. It wasn't just for show. He needed that momentum to generate the 320 Newtons of force scientists later calculated he applied to the ball.
- The Angle: He aimed for the "A" in the "La Poste" advertisement board behind the goal. It was yards wide of the post.
- The Feet: His plant foot was rock solid, allowing his left leg to act like a literal whip.
Was It Just a Fluke?
In 2017, Carlos gave an interview to L'Equipe where he admitted something that kind of broke hearts. He said the wind helped. "The ball was going completely wide, but the wind brought it back," he said.
Does that make it a fluke? Maybe. But a group of French scientists (David Quéré and his team) published a paper in the New Journal of Physics years later arguing that it wasn't a one-off accident. They developed an equation for the "spinning ball spiral."
They found that if you hit a ball hard enough from a great enough distance—specifically around 40 yards—the spiral trajectory becomes inevitable. The problem is that almost no human can hit a ball that hard and with that much spin simultaneously. It requires a specific "miracle" of physical attributes that only Roberto Carlos really possessed in the 90s.
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The Legacy of the 1997 Goal
We still talk about it because it feels like the last time football was truly "impossible." Today’s balls are designed to be more predictable. They're lighter, sure, but they don't behave like the old-school heavy leather ones that held their momentum differently.
If you want to try and replicate the free kick Roberto Carlos made famous, you need a few things. You need a lot of space—at least 35 meters—because the "spiral" needs time to develop. If you're too close, the ball just flies into the stands.
You also need to accept that you'll probably pull a hamstring.
To actually pull this off, focus on the "jolt" rather than a long follow-through. You want to impart maximum rotation with minimum contact time. Hit the bottom-right of the ball with the area of your laces just toward the outside of your foot. And honestly? Hope for a bit of a breeze from the right.
Start by practicing your "three-finger" strike (using the three outer toes' area) on a stationary ball before attempting the full-speed run-up. Focus on the ball's rotation axis rather than the power. Once the ball is spinning like a top, then you start adding the "tree-trunk thigh" power.