Michael Phelps has lost in the first final of his comeback after a 20-month retirement.
Ryan Lochte beat Phelps in the 100-meter butterfly final at the Arena Grand Prix. Lochte touched in 51.93 seconds; Phelps was second in 52.13 on Thursday night.
Phelps is the three-time Olympic champion and current world record-holder in the event. He was competing for the first time since the 2012 London Olympics.