SAITAMA, Aug 8 — A rampant United States swept past Japan to their seventh straight women's basketball crown Sunday, with Sue Bird and Diana Taurasi collecting their fifth Olympic gold medals to cap remarkable careers.

Brittney Griner scored a game-high 30 points with five rebounds and two assists as the hosts were overpowered 90-75 by a team that stretched their Olympic win streak to 55 games dating back to their last defeat in the 1992 semis.

They went to half-time with a 50-39 lead and there was no stopping them, with a valiant Japan settling for second place and a best-ever Olympic finish.

Beating the Americans in Saitama was always going to be a huge ask, with the USA one of the most dominant teams in Olympic sporting history.

They had won eight out of the past nine Olympic titles heading into the final. 

Their only blemishes in the history of the tournament were a silver behind the Soviet Union at the inaugural event in 1976 and bronze in 1992. 

Bird, 40, and Taurasi, 39, both scored early buckets as the US raced to a 13-point lead against a nervous Japan, closing out the first quarter with a 23-14 advantage and Griner already into double digits.

Japan stabilised and began making some shots but they again struggled with Griner's 6ft 7ins (2.01 metres) height in the paint as the US picked her out repeatedly and she went 9-of-10 from the floor.

They took a 50-39 lead into the second half and built it into a 75-56 edge heading into the final stretch, with A'ja Wilson contributing 19 points and five assists for the game.

Japan were led by Maki Takada with 17 points, but the US successfully restricted the dangerous Rui Machida to just six assists, after she made an incredible 18 in the semi-finals to set a new Olympic women's game record.

The Americans' seventh title equalled the longest ever streak by a team in any Olympic sport -- matching the feat of the US men's basketball team between 1936 and 1968.

Bird, who has won four WNBA titles with the Seattle Storm, and Taurasi, who has led the Phoenix Mercury to three WNBA championships, have been front and centre during the past five.

The pair won their first gold at Athens in 2004 as two of the youngest players on a team that also featured Dawn Staley, who claimed three gold as a player and is now the national coach. — AFP