Phelps won the 100m butterfly on the penultimate night of the US Olympic swimming trials on Sunday in 51.14sec to claim a fifth individual berth for London.
Phelps was nowhere near his world record of 49.82sec, but he was fastest in the world this year and ominously for his rivals, he said it was a ragged effort that could be vastly improved.
"It was a pretty crappy first 50 and a pretty terrible finish," said Phelps, who rallied from sixth at the turn to finish ahead of Tyler McGill.
McGill was fourth at the turn, but won the battle for second in 51.32 ahead of Ryan Lochte.
"It's done, we're done," Phelps said of his trials campaign, although of course he hopes the best is yet to come in London.
"It shows that I can do the kind of event programme like this at a high level again," he said. "We were struggling over the last couple years at doing one event at this level. (It's good) being able to get a couple under the belt this week and hopefully build off of this."
Phelps, whose unprecedented eight gold medals in Beijing four years ago took his career tally to 14, now can swim the same eight events in London: the 100m and 200m butterfly, the 200m and 400m individual medleys, the 200m freestyle and three relays.
Lochte is slated for four individual events, including showdowns with Phelps in the 200m and 400m medleys and 200m free and a title defence in the 200m backstroke, and will also see his schedule swelled by relays.
Even if he'd snagged one of two Olympic spots on offer in the 100m fly, Lochte said he wouldn't have tackled the event in London.
It would require the punishing treble he swam here on Saturday of the 100m fly, 200m backstroke and 200m individual medley.
"I don't want to do that triple again in London," said Lochte, who called the eight-day trials "a training meet".
"I haven't fully rested yet," Lochte said. "Come London, I'll have that full taper and be fully rested and hopefully I'll be a lot faster."
While Phelps and Lochte are old hands at multiple medal campaigns, 17-year-old Missy Franklin is poised to become the first US woman to swim seven events at the Games in her first trip to the Olympics.
Franklin's convincing 200m backstroke victory in 2:06.12 gave her a fourth individual event.
The reigning world champion, Franklin posted the fastest time in the world this year and beat runner-up Elizabeth Beisel (2:07.58) by more than a second.
"I'm so happy with my 200 backstroke," Franklin said. "I felt really strong. It really hurts so bad at the end, but if it doesn't then you're not doing it right.
"I can't believe I have seven events," added Franklin, who also has three relay berths. "It's so overwhelming but so exciting at the same time."
Anthony Ervin appeared ecstatic to line up one event in London -- the 50m freestyle.
The 31-year-old who walked away from swimming three years after winning 50m free gold in Sydney in 2000, was runner-up to Cullen Jones to secure his spot.
Jones and Ervin were impressive in the one-lap dash, their times of 21.59 and 21.60 the second- and third-fastest this year behind Beijing gold medallist Cesar Cielo of Brazil.
Kathleen Ledecky, 15, booked a first Olympic berth with a victory in the 800m freestyle ahead of Kate Ziegler.
At the other end of the swimming age spectrum, 45-year-old Dara Torres kept her bid to make a sixth Olympic team alive as she advanced to the final of the 50m free with the third-fastest semi-final time behind red-hot Jessica Hardy (24.56) and Christine Magnuson (24.72).