Sydney McLaughlin admitted after watching Karsten Warholm's record-breaking men's 400m hurdles run she felt Wednesday's women's final could see records fall.
McLaughlin smashed her own world record in her gold medal-winning time of 51.46, eclipsing her previous mark of 51.90.
The American's run means both gold medal winners ran a world record in the women's 400m hurdles and men's 400m hurdles finals at Tokyo 2020.
McLaughlin said she watched Warholm win the men's equivalent in 45.94, breaking his previous mark of 46.7, with amazement.
"When I saw the time yesterday I was amazed but not surprised," she said. "I knew it was going to be a really fast race for them. It definitely shocked me and I thought tomorrow [Wednesday] is going to be something fast."
In both 400m hurdles events, the silver medal winners ran faster than the old world record. All six medal winners ran faster than the previous Olympic records in these events.
"I'd definitely say it's a fast track," McLaughlin said about Tokyo Olympic Stadium. "You can feel the difference. It's one of those tracks which gives you the energy."
Silver medalist Dalilah Muhammad also broke the previous world record with 51.58, while Femke Bol from the Netherlands claimed bronze in 52.03 – a European record.
"Anything is possible," McLaughlin said about future world records. "You have such an amazing field of women.
"The more we race each other, anything is possible. Technically there's always more to improve upon. in terms of what's possible, it's completely limitless."
McLaughlin's gold was the 1000th won in athletics in Olympic Games history (since 1896).
CUNHA TRIUMPHS IN SWIMMING MARATHON
Five-time world champion Ana Marcela Cunha claimed the gold medal in the women's 10km marathon swim.
The Brazilian touched first in 1.59.30.8, only 0.9 seconds ahead of reigning Olympic champion Sharon van Rouwendaal from the Netherlands. Australia's Kareena Lee claimed the bronze.
Cunha finished 10th in her home games in Rio but the open water swimmer dominated in warm yet good conditions with minimal wind or current at Odaiba Marine Park.
YOUNGSTERS DOMINATE SKATEBOARDING
Japanese teenager Sakura Yosozumi won the first-ever women's park skateboarding gold medal with a best score of 60.09 in her first of three runs.
Yosozumi beat out 12-year-old compatriot Kokona Hiraki who scored 59.04 in her second run.
Sky Brown scored a 56.47 in her final run to claim bronze and become Team GB's youngest ever Olympic medallist, at the age of 13 years and 28 days.
DUTCH DELIGHT IN RIO RE-MATCH
Felice Albers scored a double as the Netherlands secured their spot in the women's hockey gold medal match after a 5-1 win over reigning champions Great Britain.
In a re-match of the 2016 Rio gold medal showdown, the world number one Dutch side proved too strong, scoring twice within a minute in the second quarter to open up a 2-0 half-time lead.
The Netherlands will be the favourites in the final, when they play either India or Argentina on Friday.
Dutch coach Alison Annan said: "This was a really solid performance and when you win 5-1 in a semi-final you can only be very happy and proud of the players and the team with the performance they put together."