On the first full day of his life as the most-decorated Olympian, Michael Phelps went back to work — those medals don't start winning themselves just because you've hit 19, after all. But first he had to attend to his correspondence.

"Thank you Mr. President!!" he wrote, re-tweeting a congratulatory message from @BarackObama. "It's an honor representing the #USA !! The best country in the world!!"

A little less formally, there was a "Thanks bro!!!" to a tweet from Lil Wayne ("High praises to my good friend Michael Phelps for becoming the greatest Olympian of all time.USA!!"). There was more gratitude to actor Josh Charles ("I'm so damn proud of my fellow Baltimore boy @MichaelPhelps"), Irish golfer Graeme McDowell, New England Patriots wide receiver and former Raven Donte Stallworth and Washington Wizards guard John Wall and fellow Olympians Kimmie Meissner, Shaun White and Apolo Ohno.

The flurry over the Baltimore swimmer's latest shattering of a record, though, had to go on mostly without Phelps' full attention. After barely sleeping in the wake of all the excitement, Phelps was back at the Aquatics Centre Wednesday morning for his fifth race, the 200-meter individual medley.

Despite the sleep deprivation and the swirl of worldwide attention, Phelps swam to the fourth-fastest finish in the morning heats, with rival Ryan Lochte coming in second going into Wednesday evening's semifinals. There, the two swam in adjacent lanes, always thrilling to watch, with Lochte winning first seed and Phelps third going into Thursday night's finals.

Phelps pronounced himself glad just to be getting back to one of the center lanes reserved for the top seeds, especially given how much was going on around him.

"I felt fine," Phelps said after his semifinal swim. "I just tried to stay focused."

Earlier in the morning, he talked about how many people he heard from — both friends and celebrities, and some who are both.

"There was like this madness. I wanted to thank all the people who sent some tweets, [President] Obama," Phelps said after his morning swim, "and [Barcelona footballer Gerard] Piquet, a bunch of different athletes from all over the world. It was pretty cool."

Obama's congratulatory tweet was followed by a phone call as Phelps was heading back to the pool for the semifinal.

Phelps said he got little sleep Tuesday night. "I must have left the dining hall at 11:30 [p.m.], got back to my room probably about 12," he said. "I do not really know what time I fell asleep."

His coach, Bob Bowman, said he doesn't think Phelps will have a problem staying motivated despite having the most medals of any Olympian. In fact, he has other milestones on the horizon.

On Wednesday, Japan's Kosuke Kitajima failed to medal in his 200-meter breaststroke event, which, had he come in first would have made him the first male swimmer to win gold in the same event in three consecutive Olympics. Phelps himself missed his first opportunity to do that, when he finished fourth in the 400 IM on Saturday.

His third chance comes Thursday night, in the 200 IM.

But to win that, Bowman said, he has to swim a stronger second half of the race than he did Wednesday night. And, he said, they had one of their discussions — voices may have been raised a bit, which is not that big a deal with these two often combative personalities — over his less-than-sharp breaststroke portion.

"I'd like to see him do a more agressive breaststroke," Bowman said, "see what happens."

This will be his last matchup against Lochte in a rivalry both say has improved each of their games.

"We love racing against each other," Phelps said. "Neither of us likes to lose. I like to say we bring the best out in each other."

They also have fun together — both are fans of Lil Wayne, for one thing, the rapper who name-drops Phelps in his songs, even dedicating "Go Getta" to him, saying, "Michael Phelps, this is for you," in the intro. After Phelps lost the 400 IM and Lochte won gold in it, the two had dinner together in the athletes village, with their coaches, Bowman and Gregg Troy, also the coach of the Olympic men's team, as other swimmers dropped by.