American Aaron Peirsol shattered his own world record in the 100-meter backstroke at the world swimming championships on Tuesday. He followed in the footsteps of Michael Phelps, who set the world record in the 200-meter freestyle, and Natalie Coughlin, who broke her own mark in the 100-meter backstroke. Peirsol won the gold medal in 52.98 seconds to slice 0.19 seconds off the previous record of 53.17 he set at Indianapolis in 2005. (WCSN, WCSN.com)