Bradly Sinden has booked a place in the final of the men's taekwondo -68kg, assuring Team GB of at least a silver medal.
The 22-year-old was trailing by seven points heading into the final round of his semi-final tie with China's Zhao Shuai but produced a stunning 24-point comeback to take the bout 33-25.
The news means that Team GB are guaranteed their first medal of the Games on a day that saw reigning female taekwondo champion Jade Jones suffer a shock defeat at the first hurdle.
In reaching the final, Sinden - world champion in 2019 - also gives himself a chance of becoming Team GB's first ever male taekwondo winner at an Olympics.
Sinden's opponent in the gold-medal contest will be 19-year-old Ulugbek Rashitov of Uzbekistan, who defeated favourite Lee Daehoon en route to the final.
The contest begins at 1.45pm UK time.