He wants to go faster -- right now.
The winningest athlete in Olympic history figured he would be putting up better times by this stage of his comeback.
"That the hard part for him," his longtime coach, Bob Bowman, said Thursday.
Phelps will get a final tuneup before the two biggest events of the year when he competes in a special meet at the University of Georgia, going against Ryan Lochte and several of the world's top swimmers.
Beginning Friday, Phelps will take part in three events over three days, another important step in showing how fit he is since coming out of retirement.
In less than a month, he'll be competing in the national championships in Irvine, California, followed two weeks later by the Pan Pacific Championships in Australia.
"It helps Michael a lot to race," Bowman said. "That's what he really loves to do. If he's just training, it gets a little old."
Phelps was not at the pool for the first day of the Bulldog Grand Slam, a short session with small fields for the women's 1,500-meter freestyle and men's 800 free. He was scheduled to arrive in Athens by the evening and be ready to go in his first event Friday morning, the preliminaries of the 100 butterfly.
Phelps will race the 100 backstroke on Saturday, followed by the 100 free on the final day.
This will be the fourth meet for the 29-year-old swimmer since he ended his retirement, but he's still feeling the effects of being away from the pool for more than a year.
He left the sport after the 2012 London Games, declaring he had met all his goals with 18 golds and 22 medals overall, far more than any other Olympic athlete.
"When you take a whole year off, that's a lot of time," Bowman said. "We would always tell him, `For every day you take off, it takes two to get back to where you were.' Well, by that, he's going to need two years to get back to where he was at London."
Three weeks ago at Santa Clara, Phelps took on the most daunting workload of his comeback by racing in four events over three days. He tied for first in the 100 butterfly, was second in the 100 and 200 free, and finished third in 200 individual medley.
That last event was especially frustrating for Phelps, who was swimming it for the first time since taking the gold in London. He led through the first three laps, but tired on the freestyle leg and was passed by both Conor Dwyer and Chase Kalisz.
Phelps' time was 1 minute, 59.76 seconds, which was right in line with Bowman's expectations.
Not so for Phelps, who once held the world record and edged Lochte in the last Olympics with a time that was nearly 5 1-2 seconds faster.
"It's hard for him right now because he's always kind of dealt in these real black-and-white terms," Bowman said. "It's hard for him to come back when he goes 1:59 or whatever it was in the 200 IM. I'm like, `Man, that was really great.' And he's like, `Are you kidding me?"'
Lochte is also in the midst of a comeback, racing for only the second time since tearing up his left knee in an encounter with an exuberant fan last November. The 11-time Olympic medalist returned for an April meet in Arizona, pushed a little too hard and wound up suffering a setback in his recovery.
Now, after a more extensive recuperation, he's ready to test his knee again.
Just in the nick of time. After the meet in Georgia, the next two events will determine the U.S. team for the 2015 world championships in Russia.
"Hopefully I'm back," said Lochte, who entered the same three events as Phelps as well as three other races, though he may drop some of them depending on how his knee feels.'
"Once I'm in the water, I'm at home. I feel normal. I was not able to do that when I hurt my knee. That's the only regret I had. But everything happens for a reason. I hope it makes me a better swimmer."