Kevin Durant scored 30 points for the United States in a victory that practically mirrored the one over Spain at the 2008 Beijing Olympics, and LeBron James closed with two huge plays in the final three minutes to effectively seal it and set off a huge celebration at the O2 Arena.
Krzyzewski pulled Durant, James and Bryant with 37.6 seconds left, amid a thunderous ovation from the sellout crowd and giant, joyful hugs from their teammates.
"Born in the USA" blared after the horn sounded, and smiling players leaped into each other's arms, danced and sang and midcourt, and even dumped water on the 65-year-old Krzyzewski who moments earlier had thrown his arms in the air and jumped off the sideline in celebration like a teenager.
"It's a great run," Krzyzewski said later. "Just a great, great run. We're very proud of it."
The gold medal capped an eight-year rebuilding process for USA Basketball after the 2004 Athens Olympics, where the once-invincible Americans won only a bronze medal and sulked home in embarrassment.
Since Krzyzewski and chairman Jerry Colangelo rebuilt the program, the Americans have won two Olympic gold medals and the last world championship, and fueled an ongoing argument about whether they are better than the original "Dream Team" from the 1992 Barcelona Olympics.
"I was one of those kids that looked back on the 1992 team and said, 'That is where I want to be,'" forward Carmelo Anthony said. "And 20 years on, here I am winning the gold medal."
Almost every player on the roster played a key role at some point or another, though the biggest stars shined brightest when their team needed them most.
The 23-year-old Durant became the highest scoring American ever in a single Olympics, reaching 156 in eight games with a clutch performance that showed once again that he's the future of the program.
Meanwhile, James "the best player," as Krzyzewski described him scored 19 points and came up with two of the biggest plays of the game while playing with four fouls, one short of ejection.
With Spain still lurking six points back with less than three minutes left, James found an open lane and drove untouched to throw down a monstrous dunk, then hit a 3-pointer on the next possession to push the American lead to nine with 1:59 left, all but finishing the job.
"I just wanted to make an impact on the game," James said. "I wasn't going to leave with [just] those four fouls."
The game was close throughout, far different from most of the games the Americans had played here.
Pau Gasol and Juan Carlos Navarro kept Spain in the game with 24 and 21 points, respectively, but the Spaniards just could not keep up at the end, despite being within four with 6:51 to go.
"I know it's nice to have another silver," Spain's Jose Calderon said. "But we were so close. We fought to the end."
Coach Sergio Scariolo will rue his decision to put forward Marc Gasol back in the game with two fouls midway through the second quarter. The team's second-leading scorer and rebounder picked up his third and fourth fouls in a 36-second span and had to sit until the fourth quarter, to avoid fouling out.
He played just 17 minutes.
"Probably was a mistake," Scariolo said. "Maybe it was just one of the risks you have to take if you want to win and sometimes things go the way you want, sometimes not. It happens."
Besieged by injuries to players who might have earned a place on the team, the Americans nevertheless proved they could win with a versatile lineup that made up for its lack of size with sheer athleticism and tremendous outside shooting.
"It means everything," James said. "A lot of people doubted us, you know, said we were too small. Said we wouldn't be able to compete with the size of a lot of teams. … It's not about size, it's the heart. It's the heart that comes through, and I'm happy we have a bunch of big hearts on our team."
Afterward, both Bryant and Krzyzewski confirmed that they will not be back.
But they leave London having helped restore basketball glory to the nation that invented the game, and allowed themselves at least to be considered among the best teams ever assembled a water-cooler argument Bryant started himself by claiming that this team could beat the original Dream Team.
One last time, Bryant was asked: Is this team invincible?
"This Olympics, we were," he said.
Storylines U.S. back for seconds
R Team USA wins its second straight Olympic gold medal, beating Spain 107-100.
• Kevin Durant scores 30 points, becoming highest-scoring American in a single Olympics.
• Coach Mike Krzyzewski and Kobe Bryant both confirm they are retiring from international basketball.