Freestyle queen Katie Ledecky made sure of her third swimming gold medal of the Rio Olympics, and fourth of her career, after anchoring the US women to victory in the 4x200 meters relay on Wednesday.
Australia took silver and Canada the bronze.
The US were the defending champions but only Allison Schmitt, who swam the leadoff leg in Rio, was in the race lineup from that London 2012 golden quartet.
Leah Smith and Maya Di Rado swam second and third respectively before Ledecky - who won the 400 freestyle on Sunday and 200 free on Tuesday -- brought home the gold.
Efimova makes second breaststroke final, King misses out
Russia's Yulia Efimova booked her place in the final of the women's 200 meters breaststroke but her nemesis Lilly King of the United States failed to make it past the semi-finals.
Australia's Taylor McKeown was the fastest qualifier for Thursday's final, followed by Japan's Rie Kaneto and Britain's Molly Renshaw, with Efimova sixth and King 12th. Only the top eight make the final.
With two past doping suspensions, Efimova, bronze medalist in the event in London 2012, was initially excluded from the Rio Games but succeeded in a last-minute appeal last week to be allowed to compete.
Comments by King describing her rival as a drug cheat set up a tense clash in Monday's 100 breaststroke final, in which the American defeated the Russian.
The two swam in separate semi-finals.
King's forthright comments earlier in the week gave an even sharper edge to traditional US-Russian rivalry.
Russian swimming chief Vladimir Salnikov told Reuters on Tuesday the atmosphere surrounding his team reminded him of the Cold War.
King, 19, told reporters earlier on Wednesday that she had no regrets for what she said.
"My parents raised me to say what I wanted to say even if it wasn't what people wanted to hear necessarily, so it's always been like how I am," she said.
"And I'm going to stick with my guns."
Phelps and Lochte set up final showdown
Michael Phelps and Ryan Lochte set up one final showdown to cap their glittering Olympic careers by qualifying first and second for the final of the 200 metres individual medley.
Racing in adjacent lanes in the second semi-final, Phelps clocked one minute, 55.78 seconds and Lochte 1:56.28, a turnaround from the morning heats where Lochte was first and Phelps third.
Brazil's Thiago Pereira, who had led the Americans after the butterfly and backstroke legs and was second behind Phelps at the final turn, qualified third in 1:57.11 to give the home country a shot at a first medal in the pool.
Japan's Kosuke Hagino, winner of the 400 IM on Saturday, won a slower first semi-final to go through to Thursday's final in fourth place.
In the same event at London in 2012, Phelps took the gold medal and Lochte won silver.
Phelps, 31, is bidding to become the first swimmer to win the same event at four consecutive Olympics, and to expand a career medal haul that has grown this week to 25, all but four of them gold.
Lochte, a year older, has 12 Olympic medals, six of them gold, and the 200 IM is his only individual event in Rio after taking gold alongside Phelps in Tuesday's 4x200 freestyle relay.
Belmonte wins breakthrough gold for Spain
Mireia Belmonte won the 200 meters butterfly to become the first Spanish woman to win an Olympic swimming gold medal.
The silver medalist in London four years ago went a step better in Rio with a winning time of two minutes, 4.85 seconds, the fastest time so far this year.
Australian Madeline Groves, who went into the race with the fastest time of 2016, took the silver medal and Japan's world champion Natsumi Hoshi won bronze.
Australia's Chalmers wins men's 100m freestyle
Australia's Kyle Chalmers won the gold medal on Wednesday in the men's 100 meters freestyle, the blue riband event in the pool.
Pieter Timmers of Belgium took the silver, and defending Olympic champion Nathan Adrian of the United States won the bronze.