Adam Peaty was beaten in the men's 100m breaststroke for the first time since 2015 at the Commonwealth Games on Sunday as England team-mate James Wilby took gold.
The world record holder was first at the turn but faded in the second 50m, as Wilby stormed to victory in 59.25sec.
Zac Stubblety-Cook took silver and fellow Australian Sam Williamson won bronze.
But the crowd at the Sandwell Aquatic Centre, who roared for Peaty when he made his way to the starting blocks, was left stunned by the defeat for the three-time Olympic champion who finished fourth.
Peaty, who has dominated his event in recent years, was forced to miss the world championships in Budapest in June due to a foot injury.
"When it comes down to the race sometimes it doesn't go to plan," Peaty said. "I was hurting from the 50m but you know that's a lack of training, lack of racing."
He added: "I can't overthink it. I'm a fighter and sometimes you have got to have these moments to keep fighting."
The 27-year-old said the Paris Olympics in 2024 were firmly on his radar.
"The next two years are going to be huge -- how we attack that now, I don't know," he said. "Because I haven't done two winter blocks in a long time so it's back to the drawing board and back to training."