"I was lucky to get in," he said, referring to his slow time in the morning. "I had a chance to put myself in a spot to start off on a good note and didn't do it."
Lochte gave the Americans their first gold medal of the London Games and put himself in position to fulfill the promise he showed at last year's world championships, where he won five golds and beat Phelps in their two head-to-head meetings.
The friendly rivals have one more showdown in London, in the 200 individual medley. Phelps edged Lochte in that race during the U.S. Olympics trials, but Lochte appears to be on top of his game when it really counts.
They might be working together on Sunday, when both are in the mix to compete for the U.S. in the 4x100 free relay.
There appear to be no hard feelings.
"Congrats to (at)RyanLochte," Phelps tweeted afterward. "Way to keep that title in the country where it belongs!!"
"Thanks," Lochte replied: "I couldn't do it without you."
Follow Paul Newberry on Twitter at www.twitter.com/pnewberry1963