RIO DE JANEIRO (Reuters) - Simone Manuel anchored the U.S. women's 4x100m medley relay team to the 1,000th gold medal in her country's Olympic history on Saturday, and the second of her career.

The United States were the defending champions and Manuel's swim came about 40 minutes after she won silver in the 50m freestyle.

The 20-year-old, who leaves Rio with two golds and two silvers, won the 100m freestyle in a dead-heat with Canada's Penny Oleksiak on Thursday.

The relay win in 3min 53.13sec was the 23rd U.S. gold of the Rio Games and, according to the U.S. Olympic committee also the 1,000th won by the country in summer competition since triple jumper James Connolly took their first in 1896.

Australia won the silver, beating bronze medallists Denmark by just 0.01sec.

Dana Vollmer, who swam the third butterfly leg for the United States, was the only one in the race line-up to have also been in the 2012 winning quartet.

Kathleen Baker was inside the backstroke world record after 50m, with Canada's Kylie Masse second, but had dropped to fourth at the handover to 100m breaststroke champion Lilly King with Denmark leading.

King, racing against Russian Yulia Efimova, whose doping past she spoke out about earlier in the week, pulled back to second with the Russians in front.

Vollmer, a bronze medallist in the 100m butterfly last Sunday, put the holders back ahead and handed over to Manuel, who powered to the finish.

The United States also won the 4x200 freestyle relay on Wednesday, again beating Australia who had to settle for silver.