RIO DE JANEIRO — It hurts more this time.

That's just reality for Michael Phelps as he attempts to win six Olympic gold medals at age 31. He added Nos. 20 and 21 of his career Tuesday night only to be rewarded with another preliminary swim, in the 200-meter individual medley, less than 15 hours later.

Phelps handled the chore without a problem — swimming the third-fastest qualifying time — because that's what he does. He later posted the top qualifying time in the nighttime semifinals.

“I've been able to put my body through things like this over the years,” he said.

But at his age, with swimmers five and 10 years his junior lining up to knock off the king, the physical toll mounts in a way it did not when Phelps was 23. If all goes according to plan, he'll swim 12 races in seven days at these games. As he noted wearily, he wasn't even halfway done with his schedule after winning two more gold medals Tuesday night.

Today will be his most arduous day, with a 100-meter butterfly preliminary scheduled for the afternoon and the 200 IM final and a 100 butterfly semifinal likely to follow at night. Phelps gulped for air and walked down the stairs like an 80-year-old man after he swam the same three races in roughly the same amount of time at the Olympic trials.

In addition to his own fatigue, Phelps will have to overcome what might be his greatest rival if he's to win a fourth consecutive Olympic gold medal in the 200 IM.

Ryan Lochte is even older than Phelps, having turned 32 two days before the games started. But he'll go into the final fresher, since he won't swim this morning and the 200 IM is his only individual event.

The pair have been swimming against each other in the 200 IM since they were teenagers. In the same 4x200-meter relay in which Phelps won his 21st gold medal, Lochte became the second-most decorated male swimmer in Olympic history.

They're linked at the hip, as rivals and in recent years as buddies. No Chad le Clos death stares between these two. They're more apt to crack each other up on the pool deck.

As Phelps sought to keep his medal train rolling Wednesday, one of his closest friends in the sport, Allison Schmitt, looked for one more golden moment in what were likely the last two races of her Olympic career.

She was a major star of the 2012 Games in London, winning five medals. Add those to the bronze medal she won in 2008 and the silver she picked up in 4x100-meter freestyle relay Saturday and Schmitt is one of the most successful Olympic swimmers in history.

She showed why Wednesday afternoon, giving the United States a big lead in its 4x200-meter relay preliminary with an explosive opening leg. She also led off as the U.S. team won gold in the nighttime final, with Leah Smith, Maya DiRado and Katie Ledecky swimming behind her.

Ledecky swam a commanding anchor leg to pick up her third gold medal and fourth medal overall of these Olympics.

Schmitt climbed to the stands to give both of her parents long hugs after she won her gold medal.

"It's been a long journey," she said. "To finish it off with a relay with those three girls, it's a dream come true"

Schmitt, 26, is swimming for a concept larger than medals at her third games. Her life took a harrowing turn in the years after her London triumph. As more and more people approached her, seeking the company of an Olympic hero, Schmitt felt less and less comfortable in her own skin.

Schmitt wanted to be happy with all the attention, to feel eager for her next training session at the pool. But she didn't, and instead of confronting her misgivings, she buried them beneath a forced smile.

Some days, she dreaded her life so completely that she never left her bedroom. Others, she arrived at the Meadowbrook Aquatic Center in Mount Washington determined to tell her coach, Bob Bowman, she was quitting the sport.

Her emotional crisis boiled over at a meet in Austin, Texas, in January 2015. During a tear-stained conversation with Bowman, Phelps and conditioning coach Keenan Reynolds, she revealed all of her pent-up anguish. From there, Schmitt entered therapy and gradually felt better. But along the way, she experienced another epiphany, prompted by terrible circumstances.

In May 2015, her 17-year-old cousin, April Bocian, committed suicide. Bocian was a well-liked athlete, just like Schmitt. And she had been in pain without anyone realizing it, just like Schmitt.

So Schmitt decided it was no longer good enough for her to heal in private. If she could save one other person by describing her own experiences with depression, she felt she had to tell the story.

That's what she has done, in addition to swimming, for the past 14 months. Schmitt could hardly speak through sobs of joy after she qualified for her third Olympic team.

“Oh, gosh, I don't remember the last time I had happy tears,” she said on that evening in Omaha, Neb.

In Rio, she has spent most of her time smiling. Not only did she win a silver medal in her first relay, she has watched Phelps — her Arizona housemate and unofficial big brother — extend his remarkable Olympic run. In the 4x200 relay, she teamed with another training partner, first-time Olympian Cierra Runge.

“I can definitely stand back and appreciate every little thing,” Schmitt said. “That's the most special part for me, being able to take it all in and appreciate being here again.”

She sounded a lot like Phelps.

Despite sleeping just five hours in preparation for his first swim Wednesday, Schmitt's buddy didn't feel too shabby.

“I guess the worst I felt was after the 400 free relay, having to be here the next morning for the 200 fly,” Phelps said. “This really wasn't that bad. My body hurt a little bit, but I think with a good rest in the afternoon, I'll be fine.”

He had been texting with his friend, former Ravens linebacker Ray Lewis, on the subject of athletic commitment.

“Leaving everything in the pool one last time is what I'm going to do,” he said.

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