GOTEBORG, Sweden -- Things didn't go quite as planned for the favorites on the first day of the World Figure Skating Championships.
A rare fall in the ice dance compulsories left Americans Tanith Belbin and Benjamin Agosto in fifth place Tuesday, five points behind leaders Isabelle Delobel and Olivier Schoenfelder of France.
Zhang Dan and Zhang Hao of China led the pairs, executing a flawless short program after Grand Prix final champions Alina Savchenko and Robin Szolkowy made two minor errors.
"We're just going to have to do what we always done: We just have to skate a strong (original dance) and free dance," Agosto said. "I think the programs we have this year are the strongest we ever had."
Belbin and Agosto arrived as favorites to win the dance titleafter European and Grand Prix champions Oksana Domnina and Maxim Shabalin withdrew because of his injury.
The Americans had devoted extra time this year to compulsories, considered their weakness.
Santa Rosa's Kim Navarro and Philadelphia's Brent Bommentre were in 12th place.
But Belbin stumbled and fell while performing a rotating turn on one foot, called a twizzle, during their Argentine tango. Falls in compulsories -- where every couple skates the same pattern for two rotations around the rink -- are extremely rare, and the Argentine tango is considered a relatively simple dance.
The Americans' score of 35.02 leaves them little margin for error in Thursday's original dance or Friday's free dance if they are to have any shot at becoming the first U.S. team to win a world dance title.
Delobel and Schoenfelder lead with 40.73 points, and Canada's Tessa Virtue and Scott Moir in second with 38.71 points.
Russia's Jana Kokhlova and Sergei Novitski were third, and Federica Faiella and Massimo Scali of Italy fourth.
"It's just a freak accident. It's never happened in practice," Belbin said. "I'm just really bummed out right now because we were really proud of this dance."
Schoenfelder and Delobel said the Argentine tango wasn't as easy as it might have been when first invented in 1934 -- given the speed and intricacy that ice dance has now developed.
"We have added more to each step," Delobel said.
Savchenko and Szolkowy beat Zhang and Zhang at the Grand Prix final in December. But it was the Chinese taking the lead Tuesday with a gorgeous triple twist and a difficult overhead lift.
Zhang Hao said he was still in pain after minor surgery on his left leg two weeks ago, but he didn't show it during an energetic program to Maksim Mrvica's "Piano Fantasy" that enraptured a near-capacity crowd, including Sweden's Crown Princess Victoria.
"This is the second time leading after for short program, and we are very happy about that," Zhang Hao said. "We hope that we can do even better" Wednesday.
Zhang Hao easily transferred Zhang Dan from one hand to the other on a difficult overhead lift, before lightly setting her down, as if she were no more than a bird.
The Chinese pair -- who won the silver medal at the Turin Olympics -- had 74.36 points. That put them more than two points ahead of the Germans, who scored 72.00. Russia's Yuko Kawaguchi and Alexander Smirnov were third with 71.42.
The free skate is Wednesday.