World records falling at Qwest Center

It didn't take long for swimmers competing in the U.S. Olympic Swim Trials to make their mark on the record book.

Both Michael Phelps and Katie Hoff won their respective 400-meter individual medley events Sunday night, and both did it in world-record times. Phelps won the event with a time of 4:05.25, beating Ryan Lochte, who also broke the world record but finished about a second behind Phelps at 4:06.08.

Not to be outdone, Hoff also set the new world standard in the finals of her event, finishing in 4:31.12. She finished almost two seconds ahead of Elizabeth Beisel.

In Monday morning's session, a world record was broken twice in consecutive heats. Hayley McGregory set a new standard in the 100-meter backstroke with a time of 59.15 seconds, breaking the mark of 59.21 seconds set by Natalie Coughlin. Not to be outdone, Coughlin stepped up in the very next heat and lowered the world record even further, touching the wall in 59.03 seconds.

And that's just the first three sessions -- there are still 12 more sessions of the U.S. Olympic Swim Trials taking place at the Qwest Center, and you can see all the action with tickets from Ticket Express -- where no event is ever sold out.