Australia chased down the United States in world record time to grab the women's 4x100m Olympic medley relay title in a thrilling race.
The Australian quartet smashed the world mark by over a second to win in three minutes 57.32 seconds.
The US got off to a flying start in the backstroke but the Australians reeled them in on the butterfly leg before powering home in the freestyle.
Great Britain finished in fifth place but were later disqualified.
The quartet of Katy Sexton, Kirsty Balfour, Georgina Lee and Kathryn Evans admitted it was a frustrating way to end their Athens Games.
"We came here with a lot of expectation but we just haven't performed," said Lee.
Evans added: "We went out to do a job and improve our ranking but I've no idea what happened."
Coughlin, the 100m Olympic backstroke champion, had put the US into a dominating position.
But Petria Thomas, the 100m butterfly gold medallist, turned the race in the Australians' favour on the third leg.
She overhauled American Thompson to give Jodie Henry a slight edge going into the freestyle anchor leg.
Henry and Thomas earned their second gold of the Games while Giaan Rooney and Leisel Jones completed the winning quartet.
Thompson's silver medal saw her overtake compatriots Mark Spitz and Matt Biondi as the most decorated swimmer in Olympic history.
The 31-year-old American's haul now stands at 12 - though her eight gold, three silver and one bronze were all won in relays.
"This is my last Olympics so it was a little bittersweet," said Thompson. "I'm feeling a little nostalgic.
"It's not the medals that count they just represent a career of hard work and all the wonderful people I met."