The Granbury, Texas, product won in 55.98, breaking the old mark of 56.06 set by Sweden's Sarah Sjostrom in 2009. It was only the second world record achieved by a female swimmer since the hi-tech suits were banned in 2010.
It came a day after the morning heats when she broke the 12-year-old Olympic record of 56.61 held by Inge de Bruijn of the Netherlands while lowering her American record with a 56.25.
"I'm just so excited to have gotten a world record and be the first female to be under 56,'' Vollmer said. "But on the other hand, I also know I can have a better finish than that, so I know I can be faster as well."
Lochte passed in relay
Payback. This time, it was France chasing down the United States - and Ryan Lochte, no less - to win another riveting relay at the Olympics.
With Michael Phelps looking much stronger than he did the night before in the 400-meter invididual medley, the Americans built a commanding lead over the first three legs of the 400 freestyle relay and never really had to worry about the defending world champions from Australia.
When Lochte dived into the water on the anchor leg, he was a half-body length ahead of the field and looking to add another gold to his dominating victory Saturday in the 400 IM. Not so fast.
Yannick Agnel, playing the chaser role that Jason Lezak did for the Americans 4 years ago in this same event, sliced through the water and was right on Lochte's shoulder as they made the flip at the far end of the pool. With about 25 meters to go, they were stroke for stroke. But Lochte, who had already competed in 1,200 meters of racing over the first 2 days, simply didn't have enough left to hold off the towering, 20-year-old Frenchman, one of the sport's real rising stars.
"I gave everything in the last 50 until he cracked," Agnel said. "In the last 10 meters, I saw that he was really cracking."
Agnel touched in 3 minutes, 9.93 seconds, having gone exactly 1 second faster than Lochte over the last 100 meters. Lochte and the Americans dropped to silver in 3:10.38.
Phelps settled for his 17th career medal - and first silver - to move a step closer to becoming the most decorated Olympian ever. He's one away from tying the mark for most career medals held by Soviet gymnast Larisa Latynina and has five more events to take down the record.