Phelps, who won a record eight gold medals at the 2008 Beijing Olympics, will be tested by US rival Ryan Lochte in four events, Thursday's 200-metres freestyle and 100 butterfly and Saturday's 100 free and 200 individual medley.
Phelps, who is also expected to swim Friday's 200 fly, is working himself into shape for July's world championships in Shanghai, the last major global showdown before swimmers hit the pool in England next year.
"I have some times that I want to hit in mind," Phelps said. "This is a chance to see where I stand for worlds. That's the biggest thing, trying to get as prepared as I can and hit all my marks before world championships.
"If I do that, then I can set up my Olympic trials."
Phelps was third behind world record-holder Lochte in the 200 IM in January at a disappointing meet in Austin, Texas, but has made progress since then.
"I feel like I'm making steps forward," Phelps said. "Over the last couple weeks, couple months, I feel like I'm heading in the right direction. I think there are some small technical things I need to work on.
"Hopefully I will be able to swim a little faster than I did in Texas."
Phelps, who owns world records in both butterfly events, is excited about the challenge awaiting him from a new generation of rivals in London and Shanghai.
"There are a lot of new people out there," Phelps said. "It's going to be fun this summer to head over to Shanghai and be able to swim with some new faces."