Demetrious Johnson stunned Georges St-Pierre with his famous armbar lesson.
On his YouTube channel, Johnson broke down the 'Mighty Wizbar' that submitted Ray Borg in October 2017.
What happened?
Johnson and St-Pierre trained together, swapping techniques from their games.
Johnson taught St-Pierre the 'Mighty Wizbar', a flying armbar that became one of his signature moments.
Why it matters for Demetrious Johnson
The 'Mighty Wizbar' was part of Johnson's peak identity, with four UFC armbar finishes against John Moraga, Kyoji Horiguchi, Wilson Reis, and Borg.
Johnson explained that sneaking his head into position helped bait the opponent into throwing an elbow.
What comes next?
Fans may see more of this duo together, as they build a series on YouTube to grow their channels.
St-Pierre's reaction showed how rare the movement still looks, even to another all-time great, saying "That's amazing. Wow, that's insane, bro!".
Johnson dominated the UFC flyweight division with 11 consecutive title defences.
St-Pierre ruled welterweight before later winning the middleweight belt, making their training session more than a routine technique exchange.
The two legends are central to MMA's greatest-of-all-time debate.
Their latest YouTube training session was more than just a technique exchange, with Johnson sharing his expertise with St-Pierre.
Johnson's armbar finishes were a key part of his success in the UFC.
He used the 'Mighty Wizbar' to submit Ray Borg in October 2017, a finish that became one of his signature moments.
St-Pierre was impressed by Johnson's technique, reacting with surprise and admiration.
The two legends are building a series on YouTube, giving fans a glimpse into their training and techniques.