Ryan Lochte will not have the opportunity to defend one of the gold medals he won at the 2012 Olympic Games.
Lochte failed to qualify in the 400-metre individual medley, an event he dominated four years ago, at the United States Olympic swimming trials on Sunday.
He built a sizable lead during the first two legs of the event, but fell behind in the breaststroke and freestyle to finish third.
Chase Kalisz came home in four minutes, 9.541 seconds to win and Jay Litherland (4:11.021) finished second.
Both will compete in their first Olympics at the Rio Games.
Lochte cited a sore groin muscle he pulled during a morning practice heat for his 4:12.021 finish.
"[I] had to go out faster than usual, because I couldn't use my legs in breaststroke," he said, via the Denver Post. "I did everything I could in that race."
Lochte added he thought about scratching himself from the event "but it's the Olympic trials. If I had a broken leg, I'd still go out there and swim".
Lochte, who earned a total of five medals at the 2012 London Games, has swam the 400 IM just nine times since, failing to earn a single international medal in the event during that span.
The 31-year-old is also entered in the 100- and 200-metre freestyle, 200-metre backstroke, 200-metre IM and 100-metre butterfly events as he looks to qualify for each of the three relays.