RIO DE JANEIRO (AP) — They were both at a loss for words: the 33rd-seeded archer for what he just did. The top-seeded competitor and world-record holder for losing any chance at what looked to be a surefire Olympic medal.

This shock was quite a tournament changer.

Indonesian archer Riau Ega Agatha stunned Kim Woojin of South Korea 6-2 during the round of 16 in the men's tournament Monday at the Rio de Janeiro Games. It was one of several surprises on a windy day at the Sambadrome.

Kim was a heavy favorite, especially after setting a world record in qualifying. That's why he had such a dazed look after walking off the field, his tournament over. Ega Agatha was just as taken aback.

"I am a little surprised," said Ega Agatha, who entered the Olympics ranked 29th in the world. "I beat the No. 1. Things are good. I did it."

Very few thought he could. Very few thought anyone would beat Kim, who shot a score of 700 to set a recurve record only three days ago.

Some betting sites — yep, you can wager on archery — had Kim as a huge 4-5 favorite. The next closest was his teammate, Ku Bonchan, at 5-2. Brady Ellison of the United States is listed at 7-1.

The upset was certainly a stunner to the second-seeded Ellison.

"As well as he's been shooting? He's been phenomenal all week," said Ellison, who begins his first match Tuesday. "But (Kim) got out there and couldn't hit a 10. I've been out there in the same situation. It happens to all of us."

Kim helped the South Koreans to a gold medal in the men's team competition Saturday by placing five of his six arrows in the top ring. Against the 24-year-old Ega Agatha, he put only four of his 12 arrows inside the 10 range.

"I prepared a lot," Kim said through a translator. "I really regret that I didn't do well."

Ega Agatha took up archery when he was 10 after his mom got upset with him for constantly staying out late. She wanted a place where he could go and not get in trouble.

Archery provided the solution.

"All Indonesians will be shocked," said Raja Oktohari, the Chef de Mission of Indonesia. "Of course we still have another (match) that we have to prepare. Our athlete in Rio has to focus. This glory only lasts for an hour. After that, that's it. We have to prepare again."

Ega Agatha will face Mauro Nespoli of Italy in the next round. Beyond that, he won't let his mind wander.

"A very big surprise for me. But I have to stay focused," Ega Agatha said.

Another upset occurred on the women's side when 51stt-seeded San Yu Htwe of Myanmar knocked off 19th-seeded Mackenzie Brown of the United States. Brown said she simply ran into a shooter who couldn't miss.

"I shot really well, did what I wanted to do at my first Olympic Games," Brown said. "I'll come back even stronger for 2020."

A crazy day at archery, which also included No. 41 seed Witthaya Thamwong of Thailand advancing.

Asked if things opened up in the men's competition with the upsets, Ellison shook his head.

"Did you see what just happened to (Kim)? It can happen to happen to any of us," Ellison said. "There are certain people everyone wants to beat. They know it's going to be a hard match so they really don't expect to beat you. They relax and shoot — and shoot good."