Japan laid down an ominous marker on the opening day of the Rio 2016 judo test event at the Carioca Arena 1 in the Barra Olympic Park, with Chishima Maeda and Joshiro Maruyama each claiming gold.
Maeda, a 19-year-old rising star who won a bronze medal at the 2013 World Cadet Championships in Miami, overcame Brazil's Jessica Pereira of Brazil in the final of the women's under 52 kilogram category.
Chelsie Giles of Britain beat another Brazilian in Layana Colman in one of the two bronze medal bouts.
Raquel Silva overcame Helena Kuwabara in an all host country clash for the other place on the podium.
Maruyama beat Brazilian Lucas Goday in the men's under 66kg final.
Britain claimed a second podium position courtesy of LCommonwealth Games championAshley McKenzie.
Home fighter Guilherme Goes claimed the other bronze medal.
The test event is billed as a key opportunity to work out what improvements need to be made ahead of the Games.
The first noticeable fact is that the "atmosphere promises to be very good this summer", a statement from the International Judo Federation (IJF) claimed.
The IJF added that "already today an enthusiastic audience came to the Carioca Arena to watch some very interesting judo".
More than 105 athletes in four weight classes are competing at the two-day test event.
A total of 20 countries are competing, with one each from France, Great Britain, Germany, Japan and Lebanon plus 15 from the Brazil.
The Olympic judo competition is due to be held at Carioca Arena 2, with the Paralympic event at Carioca Arena 3.