BEIJING, AP:

For the world's best sprinters, passing the baton in the 4x400m relay is about as easy as rolling out of bed in the morning.

Picking a winner in that race used to be easy, too. Not anymore.

An awkward exchange between United States' sprinter Allyson Felix and her teammate, Francena McCorory, played into a razor-thin loss to Jamaica at the world championships yesterday. The American women fell by 0.31 seconds and settled for a second straight silver at the worlds after winning the Olympic and world championship titles five straight times.

"It's hard, this one," Felix said. "But it's motivation for next year."

Next year is the Olympics in Rio de Janeiro, and from the US perspective, the planning can't start soon enough.

Yes, the United States won the most medals for the sixth straight time at the worlds, dating to 2005. But it did so with only 18. That's seven fewer than the last worlds, 11 fewer than the London Olympics and the lowest total at the worlds since 2003, when the Americans won 16, after four were taken away for doping.

"When you're number one, it's always a steeper pinnacle," USA Track and Field president Stephanie Hightower said. "And staying on top is always a lot harder than when you've got to work your way to the top."

The US team certainly had some high notes. Exhibit A yesterday: A come-from-behind anchor leg by LaShawn Merritt in the men's 4x400 that closed out the nine-day meet.

The second-place finish a few minutes earlier by Felix and company ensured the United States would not win the most gold medals at this meet. Thanks to the relay upset, and a gentleman named Usain Bolt, Jamaica tied Kenya for the lead with seven golds, one more than the Americans. Felix walked away with a gold in the 400 and a pair of silvers, one in each relay, to push her career total to 12 medals at the worlds.There was no shame losing to Jamaica's speedsters in the 4x100m.

Losing to Jamaica in the 4x400m is a different story.

The fact that part of the problem was a baton exchange is a real head-scratcher. It's nowhere near as technical a hand-off as in the short relay, where the timing has to be just right and there's virtually no room for error. It's such a non-issue in the long race that when McCorory was asked what happened on the exchange, her response was: "Something happened with our exchange?"

Um, yes.

Ever-so-slight PAUSE

When McCorory reached back with her left hand to receive the baton from Felix for the anchor leg, she grabbed air. That forced McCorory to pause ever-so-slightly to grab the stick on the second swipe. The whole thing took less than a second, but the race was decided by 0.31.

"Obviously, you don't want that to happen," Felix said. "You need every inch."

On Saturday, the men got disqualified from the 4x100m for an exchange out of the passing zone, marking the eighth time since 1995 at the worlds or Olympics they had either been disqualified or failed to finish.

Still, the US finished with six fewer medals and one fewer gold than at the last big meet in Beijing - the 2008 Olympics.

That performance triggered a top-to-bottom review of the operation called 'Project 30' - a nod to the goal of winning 30 medals at the London Olympics.

There doesn't appear to be any such plans in the works after this performance, though. Clearly, this is a time for looking forward, not back.

"There's a lot of intensity and a lot of pressure and a lot of high expectations for our athletes," Hightower said. "I'm confident they'll rise to the occasion when it's necessary."