When it was done, there wasn't that water-pounding celebration we've seen so many times from Phelps - just a slight smile as he hung on the lane rope, gazing up at the stands and soaking it all in.
"Going into every call room, I said it's my last semifinal or my last prelim," Phelps said, reflecting on a busy day that included a morning swim, then two more races in the evening. "We're kind of chalking up all the lasts of certain things."
As he stepped on the medal podium - yep, that familiar top rung - Phelps' eyes were glassy, and he whispered something to Lochte. Then, staring up at the U.S. flag while the national anthem played, he bit his lip and seemed to be struggling to hold back the tears.
Phelps has never been too revealing with his emotions away from the pool.
But, with just two days to go in his swimming career, there's a definite chink in the facade. He's starting to look as human out of the water as he is superhuman in it.
"To be able to win the gold medal and be the first to three-peat, it means something," said Phelps, whose first gold in London was swimming the anchor on the 4x200 freestyle relay. "It's pretty special and something that I'm very happy for."
So a farewell Games that started as a bit of a disappointment is definitely looking up. He's now won two golds and two silvers in five races - not the eight golds in eight races in China, but a more-than-fitting capper to a brilliant career that still has two more races to go: the 100 butterfly Friday and the 4x100 medley relay Saturday.
Lochte settled for silver in 1:54.90, and Hungary's Laszlo Cseh took the bronze, well behind the Americans in 1:56.22.
"Always chasing Mike and Ryan," Cseh moaned. "It's really hard because those two swimmers are really good."
Ever the competitor, Phelps had hoped to go even faster, looking to not just win gold but take down Lochte's world record of 1:54.00 from last year's world championships.
"I wanted to push the first 100 as much as I could just to kind of see what would happen," Phelps said. "Somebody told me with like 25 to go I was under world-record pace, so it was kind of frustrating I fell a little short."
When Phelps was done with Lochte, he hopped out of the pool and dashed to the nearby diving well to warm down, preparing for a semifinal of the 100 fly. He was the top qualifier in that one at 50.86 - more than a half-second ahead of South African Chad le Clos, who upset Phelps in the 200 fly, and setting up an additional rematch with Milorad Cavic, the outspoken Serbian who still seems to think he got to the wall first when he lost to Phelps by a hundredth of a second four years ago.
Cavic is talking a different game now.
He doesn't think he - or anyone else - has a chance against Phelps in the last individual race of his Olympic career.
"Phelps is out of our league," Cavic said. "It's not fair that I'm talking for everybody, but I'm expecting something special tomorrow. I think he's going to go 50.5.
Lochte went through the same warm-down routine in the diving pool as Phelps, trying to pull off an impressive double 31 minutes apart. He came up short in both races, fading to bronze in the 200 backstroke behind fellow American Tyler Clary, then touching after Phelps in the medley.
Lochte shook hands with his rival before crawling out of the pool for the last time at these Games, though he intends to keep on competing through the Rio de Janeiro Games in 2016. In a symbolic gesture, he tossed his cap and goggles into the crowd, his work done. His final tally: two golds, two silvers, one bronze, and a fourth-place finish - impressive, but undoubtedly shy of what he had predicted would be "my time."
This time still belongs to Phelps.
At least for a couple more days.