MESA, Ariz. -- Michael Phelps is 0-for-1 in his comeback to the pool.
The 22-time Olympic medalist lost to Ryan Lochte in the 100-meter butterfly final at the Arena Grand Prix on Thursday night.
Lochte touched first in 51.93 seconds, second-fastest in the world this year. Phelps took second in 52.13 in his first meet since retiring after the 2012 London Olympics.
"I swam a final again," a smiling Phelps said. "I said I wanted to be around 52.0 and I would be completely happy with that."
He is the three-time Olympic champion and current world record-holder in the event. His time tied for fourth-quickest in the world.
"It's one meet; it's one race," Phelps said. "It's a long way whether I decide to continue or not. This was awesome. I'm really excited about how things went. I do know what I need to do if I want to continue and swim faster."
Olympian Jason Dunford of Kenya finished third in 53.08.
Phelps was faster in the final than he was while winning his preliminary heat with a time of 52.84.
"My stroke was a little rushed tonight," he said. "It was way more relaxed this morning."
Swimming before a sellout crowd and lots of cameras, Lochte led at the turn and Phelps was second.
"Down there at the turn I kind of peeked over and I saw him and almost started smiling," Lochte said about his longtime friend and rival.
Phelps interjected, "Why? Because you were ahead?"
An on-deck interviewer reminded Phelps that his mother has said she wants to go to Rio for the 2016 Olympics, which would be his fifth.
"Whatever he wants," Debbie Phelps shouted from the stands.
Phelps replied, "Good mother."
Phelps wasn't smiling as he walked on deck for the final, unlike in the prelims. He kept his ear buds in until he was introduced as an 18-time Olympic gold medalist. With his long hair sticking out from the back of his cap, he dived in next to Lochte, who beat him down to the first turn.
"I probably wouldn't have gone that time if Phelps wasn't in that pool with me. We push each other all the time," said Lochte, whose rivalry and friendship with Phelps dates to 2004.
"With what he's done for the sport of swimming and him leaving kind of broke my heart a little because I love getting on those blocks and racing him. Now that he's back, I've got a big ol' smile on my face."
Lochte is trying to regain his own form after missing five months with a knee injury. He changed coaches and relocated from Florida to Charlotte, N.C., after the London Games.
Coach Bob Bowman said Phelps was better technically in the morning than at night.
"He missed a whole stroke on the turn," Bowman said. "My expectations were he would come and maybe enjoy it and not be terrible, so all those were met. That's a really good time to start with."
Phelps said "that may have been the worst turn that I have ever done in my entire life."
Next up for Phelps is the 50 freestyle Friday, when he will swim the prelims doing the butterfly stroke for training.
Earlier Thursday, retired speedskater Apolo Anton Ohno, the most decorated U.S. Winter Olympian, tweeted good luck to Phelps, saying, "Excited to see you back brother."
The three-day meet sold out every session the day Phelps' comeback was announced last week, with a capacity of 1,200 at Skyline Aquatic Center. A pair of $40 all-session tickets was being advertised online for $250. USA Swimming issued 100 media credentials -- five times more than usual.
The possible future of American swimming finished second in the C final of the 100 fly. Michael Andrew, a 15-year-old from Lawrence, Kansas, was runner-up to Olympian Matt Grevers. He has broken more than 30 national age-group records and last June became the youngest U.S. male swimmer to turn pro. He was excited to meet his idol Phelps on Wednesday.
"Swimming needs you!" he tweeted after they traded handshakes. "You rock!"
Both of Phelps' times were easily good enough to surpass the qualifying standard of 54.79 for the U.S. national championships in August. That meet will decide the team for next year's world championships.
"One step at a time," he said in the morning.