Starting Wednesday, with the opening of the U.S. Olympic swimming trials in a makeshift outdoor pool, the world will begin to get an idea of how far Maryland's superstar swimmer, Michael Phelps, might be able to push his lean, sculpted body.

Phelps's quest for seven, or more, gold medals at next month's Olympic Games in Athens officially begins here Wednesday morning, when he swims the preliminary race in the 400-meter individual medley, the first of six events in which he is entered during the eight-day Olympic trials.

"This is a way to test how strong I am, how ready I am," he said Tuesday. "Right now I'm feeling fairly confident. . . . We want to test my max. And we want to see how much we can do."

If Phelps, 19, can win seven gold medals in Athens, he would equal the unprecedented feat of the legendary Mark Spitz during the 1972 Munich Olympics. Seven gold medals also would earn Phelps a $1 million bonus from his chief sponsor, Speedo swimwear company.

The trials have brought 700 of the nation's top male and female swimmers to Long Beach Aquatic Center to compete in 13 events that will determine the U.S. Olympic team. In most cases, the top two finishers in each event will make the team. None of the three relay events is on the program here. The members of the relay teams will be selected later.

Everyone is wondering what Phelps might do. Even Spitz, the 54-year-old Los Angeles stockbroker whose record Phelps could threaten.

"I'm just as curious as the next person, to wonder how he's going to go about doing this," Spitz, gray-haired and clean shaven, said in a rare news conference adjacent to the pool Tuesday. "Because there are a lot of interesting things he has to take care of. . . .

"I find it fascinating. I find it interesting that someone has decided to take that challenge. I think it's a great opportunity for Michael. I think it's a great opportunity for swimming."

Phelps's program, if he sticks to it, will entail swimming 17 times over six days. He does not swim the last two days of the meet. He is entered in the 400- and 200-meter individual medley, and the 200 butterfly, events in which he holds the world records. He also will swim the 200 freestyle, in which he holds the American record; and the 100 butterfly and 200 backstroke, in which he is the world's second fastest.

He could scratch from any event at the last minute. His coach at North Baltimore Aquatic Club, Bob Bowman, said they will take it one day and one event at a time, although he expects Phelps to cruise through the program.

Most days there are morning and evening sessions. On two nights, if he sticks to his schedule, Phelps will have to swim twice in a 21/2-hour period, and on Monday he will have to swim three times in short order -- twice against arch rivals. He could face the same kind of grueling "triple" at the Olympics.

"Once the swimming starts, for me personally, I take one event at a time," Phelps said at a news conference. "It's going to be one by one by one. I'm not going to worry about all six of the individual events.

"We have exactly a week pretty much of racing and competing, and trying to do everything that we can to recuperate and get back for the next race. So we definitely have a challenging schedule ahead of us."

Phelps, while saying he wants to do something in his sport that nobody has ever done, also maintains officially, and modestly, that his goal is one Olympic medal. But on Tuesday, asked how many gold medals he could win in Athens, he joked: "I can win 15 gold medals if I want to," quickly adding, "Best-case scenario, I win one."

The comment made his coach cringe. "I was hoping I didn't hear that," Bowman, 39, said. "It was a total joke. I'm sure he was joking."

He said he believes that Phelps still has not reached his potential, though this is the time of his career when he could be at his best.

"I don't know that he'll be in a position like this at any other time of his life," Bowman said. "He's fit enough. He's got a sound base of training. He's young enough to bounce back. His body's in a good place right now. As he grows and gets bigger and stronger it'll be tougher to do a 400 IM and then come back and do something else at a high level."

Bowman said Phelps often feeds off the excitement of a crowd, and the trials will feature large crowds. The pool is surrounded on four sides by scaffold bleachers that seat 10,000.

"You'll see him," Bowman said. "He'll look very relaxed behind that [starting] line."

Standing in Phelps's way this week are his two main rivals, Aaron Peirsol, the world record holder in the 200 backstroke, and Ian Crocker, the world record holder in the 100 butterfly. Peirsol beat Phelps twice during a meet in May, in the 100 and 200 backstrokes. Crocker defeated Phelps last summer in setting the world record in the 100 butterfly.

Phelps could swim against both Monday night. Peirsol said he was glad to defeat Phelps in May. It proved Phelps was human, he said Tuesday. But even Peirsol is impressed with Phelps's reach for seven gold medals. "I think it's noble of him to try," he said. Can Phelps nab seven? "I'm sure he can," Peirsol said. "Honestly, I'm sure he can. If anyone can."

Michael Phelps, 19, is one of 700 swimmers who want to make a big splash at trials.