Michael Phelps rallied to win the men's 100m butterfly here Friday, claiming the title for the third straight Games for the 17th gold medal of his Olympic career.
One last time in the 100m fly, Phelps made it a nail-biter, recalling his thrilling victory by one one-hundredth of a second over Milorad Cavic in Beijing and his triumph by four-hundredths of a second over compatriot Ian Crocker in Athens.
"This was a bigger margin of victory than the last two combined, so we can smile and be happy," Phelps said. "It was fun."
Just as he did four years ago, Phelps rallied from seventh at the turn, winning in 51.21sec.
South African Chad le Clos and Russian Evgeny Korotyshkin shared silver, both clocking 51.44.
Cavic, who famously finished a fingertip out of first in Beijing, went out hard in an effort to turn the tables.
He led at the turn but faded to finish equal fourth with Germany's Steffen Deibler in 51.81sec.
"I am just happy that the last one was a win. That is all I wanted coming into tonight," Phelps said of his last individual effort at the London Aquatics Centre. He'll complete his seven-event programme with the medley relay final on Saturday.
Phelps also narrowly beat Cavic at the 2009 world championships in Rome, where the Serbian ratchted up the pressure going into the final by beating Phelps' world record in the semis and urging Phelps to try one of the polyurethane super-suits for their head-to-head.
But in Rome, too, Phelps came out on top, rallying from fourth and regaining the world mark in the victory.
Cavic, who has been hindered by a back injury, said he couldn't have done more in his own swimming finale.
"There's not a doubt in my mind that I left everything that I had inside of that pool," he said.