RUGBY fans were treated to a first after Ollie Chessum was taken off with a head injury following an alert from his mouthguard.
The never-before-seen incident occurred during the first half of England's massive 16-14 Six Nations comeback win over Wales at Twickenham on Saturday.
Chessum had only just returned to the pitch following a yellow card 10-minute sin bin for a high tackle.
The ace took the ball before driving forward into his Welsh opponents.
But Chessum was accidentally struck in the head by a stray shoulder as he was tackled to the ground.
And straight away, his mouthpiece's latest technology kicked in to warn of a head injury.
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World rugby adopted the "game-changing" G-force tech after the World Cup in October.
It can sense the power of a hit to a player's head.
And if the collision is deemed high, it sends a signal showing the egg-chaser needs to be checked over by medics.
Law-makers introduced it in a bid to stop concussions in the game.
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And Chessum was replaced by Dan Coles for 10 minutes for checks before returning to the game.
But England received little in the way of joy with and without Chessum on the pitch.
Despite starting well, Red Rose found themselves down 5-14 at Twickenham by half time.
Ethan Roots also received a yellow card halfway through Chessum's sin-bin, meaning England were forced to play for five minutes with just 13 men.
But the hosts bounced back in style in the second half to thrillingly win 16-14.