Former junior world champion Anna Korakaki took gold at senior level by winning the women's 10 metres air rifle at the International Shooting Sport Federation World Championships in Changwon, South Korea.
It came on a day when hosts South Korea took gold and silver in the mixed 10m air pistol team event.
Greek shooter Korakaki won gold and bronze medals at the Rio 2016 Olympics and beat Serbia's defending world champion Zorana Arunovic in the final today.
Korakaki scored 241.1 points to move in front of Arunovic with 239.8.
Despite leading for much of the event, South Korea's Kim Boni faltered in the last two shots and took bronze for the hosts with 218.8 points.
Chinese shooter Wang Qian came fourth and will qualify alongside the top three for Tokyo 2020.
Korakaki said: "This is massive, I am speechless.
"This is a great day for me.
"I won this title at my first try.
"In 2014, at the last ISSF World Championship, I was still competing among junior athletes.
"Winning a quota place feels amazing.
"This means I can now take a long break before starting my preparation for the Games.
"There are still two years to go, and I will need to recharge the batteries after this Championship.
"I started-off today's final in a nice way, then I had some troubles.
"I was able to recover in the second part of the match.
"The Korean shooter was far ahead of me, but she made some mistakes, allowing me to get closer and finally to overtake her."
In the team event China took first place, setting a world record score of 1,739 points, followed by hosts South Korea just five points behind and Russia in third.
The hosts enjoyed further success in the 10m air pistol mixed team event, securing gold and silver ahead of India.
The 52nd ISSF World Championship in all events will continue tomorrow with the 10m air rifle mixed team junior and the 10m air pistol women junior finals.