"It feels absolutely amazing," Godsoe told Universal Sports. "I knew for the 50 fly, if you have a lane, you have a shot."
Godsoe, a Stanford assistant coach, was the USA's lone representative in the event after winning it at the Phillips 66 National Championships in June.
Godsoe sped to a 23.05 clocking — ranking him No. 8 in the world this year — while trailing only Cesar Cielo of Brazil (23.01). Godsoe qualified eighth in 23.16. The American record is 22.91 by Bryan Lundquist in 2009.
"Coming in lane 8, I knew I had no pressure," Godsoe said. "I just had to execute. The 50 fly is just one of those events where if some of those guys are trying too hard, they're going to be a little bit slower. So I knew if I could go a tenth or two-tenths faster (than I swam in semifinals), I'd have a chance to medal in it."
Godsoe said the race set him up well for the 100 fly later in the week (Saturday).
"I'm really excited for the 100," he said. "I knew coming in if I could match, or even come close to my 50 time, I was going to have a great 100. For me to go three-tenths faster, I've got some speed in me."
Godsoe's time of 51.66 in the 100 fly ranks him No. 4 in the world and No. 1 in the U.S. this season.
The former NCAA champ is not entirely new to the international scene. He won silver medals in the 100 back and the 100 fly at the 2011 Pan American Games, but this is the first time he's competed at a long course world championships.
American Ian Crocker won silver in this event three times — in 2003, 2005 and 2007 — but no American has ever won gold in the 50 fly at a long course world meet.
Cielo, meanwhile, became the second man to ever claim the sprint fly title twice since its inception at the 2001 World Championships.
Godsoe also has a leg on the 400 medley relay to swim this weekend. His performance in the open 100 fly likely will determine if he swims the relay finale. The Americans currently rank No. 4 in the world in the medley relay, a 3:38.03 from the World University Games.
Heading into events Thursday — halfway through the meet — the USA's medal count at Palau Sant Jordi Pool stood at 16. American swimmers have seven gold, five silver and four bronze. They lead all teams in both gold medals and total medal count.
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The men's 400 free relay team representing Stanford Swimming won the event at the U.S. Open on Wednesday at the William Woollett Jr. Aquatics Center in Irvine.
The foursome of Christopher Pickard, Aaron Wayne, David Nolan and Jason Dunford clocked 3:19.88 for the victory.
Earlier, Nolan finished eighth in the 200-meter backstroke (2:03.28) and Mary Olsen of Stanford Swimming was sixth in the women's 200 breast in 2:31.37.
The U.S. Open got under way Tuesday with five local athletes competing int he finals.
In the men's 200-meter fly, Stanford grad Bobby Bollier finished third in 1:57.32 while current Cardinal Tom Kremer from Sacred Heart Prep was fourth in 1:57.73. Both improved upon their prelim times in the morning.
In the women's 100 free, Stanford's Lia Neal was fourth in 55.32 with teammates Maddy Schaefer fifth in 55.34 and Felicia Lee seventh in 56.00.
Stanford Swimming also finished second in the women's 400 free relay with the team of Schaefer, Julia Ama, Annemarie Thayer and Lee clocking 3:44.43.