Barcelona - Missy Franklin and Ryan Lochte might end up swimming in the same event.
Swimming's governing body voted Friday to include two different mixed-gender relays — the 4x100m freestyle and the 4x100m medley — at future world championships.
Teams will be made up of two men and two women, and it is up to them to decide the order — so, for instance, a woman could race against a man on the anchor leg.
Having already been tested at a World Cup meet in Dubai last year, the mixed relays will get their official debut at the 2014 short-course worlds in Doha, Qatar, in the 4x50m format.
Then they will make their long-course worlds debut in Kazan, Russia, in 2015.
The event got rave reviews when it was tried at the 2007 Duel in the Pool in Australia, when Libby Lenton (now named Trickett) swam what would have been a world record when racing against Michael Phelps.
"It's really exciting to have another event," said American veteran Natalie Coughlin, the winner of 12 Olympic medals.
"The first time I saw it on a program was Duel in the Pool.
"I was begging to be on that relay.
"I'm still upset I wasn't on that relay.
"It's fun from team dynamic to combine our teams.
"When you're someone like me who's been here a long time, it's fun to change things up."
The addition of two more races means that five relays will be on the program at the worlds, joining the traditional 4x100m free, 4x200m free and 4x100m medley.
At the World Cup meet in Dubai, Britta Steffen — who holds the world records in the 50m and 100m free — led Germany to victory by holding off two fast-charging male swimmers in the anchor leg.
"It makes things really interesting for the spectators," U.S. women's head coach Dave Salo said.
"The athletes enjoy it on the short-course circuit.
"It's a good chance to entertain the spectators.
"That's what we're here for."
The mixed relays have not yet been approved for the Olympics.
"But that could happen, eventually.
"Of course, why not?" Coughlin said.
"It's another medal opportunity for everybody.
"Hopefully it won't make the Olympics 10 days long for us."
The pool swimming competitions at both the worlds and Olympics currently last eight days.
Also Friday, Julio Maglione of Uruguay was re-elected to a second four-year term as FINA president.
He was the only candidate.
And adjustable starting platforms were approved for backstroke races, while under-water cameras were rejected for judging.
The under-water cameras were proposed after South African swimmer Cameron van der Burgh admitted that he used an illegal dolphin kick in winning the 100m breaststroke in world-record time at last year's London Olympics.
"I think it's a mistake," Salo said of the under-water cameras.
"We should take advantage of all the technology we have to keep our sport bound to the rules."