Fatigued, Allyson Felix faltered down the stretch and fell short in her bid for a fourth straight 200-metre world title.

Energized, LaShawn Merritt rallied the Americans from a deficit on the last turn in the 4x400-metre relay to win gold and save the squad from what would have been an embarrassing loss.

This was simply that kind of night for the United States at the world championships: Plenty of highs (long jumper Dwight Phillips winning a fourth title) and plenty of lows (the mighty shot putters shut of a medal).

And there were plenty of others shockers as well, such as Carmelita Jeter adding a silver medal in the 200 to her gold in the 100 earlier in the week.

For the Americans, this performance wasn't nearly as enthralling as the team's bountiful 30-minute span the day before, when they won three surprise gold medals, but it was a lucrative haul nonetheless.

With a four-medal showing, the United States ran its count to 16, three ahead of Russia. Although, not all the medals were the colour the Americans were envisioning yesterday.

Felix came into the 200 as the overwhelming favourite. But she stepped outside her comfort zone at worlds this year, trying to run the 400 as well. All the rounds finally caught up with her in the 200 final. She just couldn't catch Jamaican gold medalist Veronica Campbell-Brown or Jeter, winding up with bronze.

This will make her think twice about attempting the 200-400 double at the London Olympics.

“If I had to say right now, it wouldn't be high on my list of things to do,” Felix said. “But things change.”

Nothing has changed for Phillips, who captured his fourth long jump title since 2003.

Fittingly, he was given the bib number 1111 for the competition. Phillips was all too eager to let the crowd know the significance, too.

With his win wrapped up, Phillips ran through the sand pit on his last jump, ripped his bib number off and proudly held it aloft.

“It was meant for me,” said Phillips, who was sidelined earlier in the season with a left Achilles' tendon injury. “Nobody believed I could do this.”

Just like nobody believed the Americans could fail to pick up a medal in the shot put because, well, they've earned at least one at every worlds since 1991.

And that was despite four throwers in the final, including defending champion Christian Cantwell, who had the best finish at fourth.

“I can't put into words what I'm feeling right now,” Cantwell said. “I want to hide and put my head under a rock.”

The 4x400 relay squad nearly knew that feeling, trailing for a good chunk of the race. But Merritt found another gear coming out of the final bend and blew past everyone.

“The race was closer than we thought, than we expected,” Merritt said. “I got the baton and did my job, came home and added another gold for the US”

David Storl of Germany broke an American stranglehold in the shot put with a toss of 21.78 metres, beating Dylan Armstrong of Canada and Andrei Mikhnevich of Belarus. United States shot putters were shut out of the medals for the first time in two decades.

Maria Abakumova of Russia flirted with the world record in the javelin but had to settle with a championship-record throw of 71.99 metres to win the javelin. World-record holder Barbora Spotakova of the Czech Republic took silver and Sunette Viljoen of South Africa earned bronze.