The defending world champion finished his quarterfinal race in 10.09 seconds, second behind NCAA champion Richard Thompson of Trinidad, to advance easily to the final 16 in track and field's glamour event.
"It felt pretty relaxed," Gay said when finally persuaded to stop just for a second to offer an update. "I just wanted to make it through."
He did, in ideal running conditions - a clear day and evening that broke from the muggy haze which had enveloped the capital during these games. World record-holder Usain Bolt and fellow Jamaican Asafa Powell also coasted through, keeping alive a potential dream final matching three men who own the eight fastest times in history.
An American dream fizzled in the shot put, where there was no U.S. winner, much less a U.S. sweep.
The best the U.S. could do was a silver for Christian Cantwell after 2007 world champion Reese Hoffa fouled on his last two attempts and finished seventh and Adam Nelson, a two-time silver medalist, threw with hurt ribs and didn't make it into the final eight.
"They anointed us as the dream team, but we're not so dominant," Hoffa said. "We're human. We're susceptible to making mistakes on the biggest stage, and it showed."
Squandering two medals is no small thing in the big picture. America led China 46-41 in the overall Olympic medal count after Friday's action and the race to win that contest is expected to go down to the end.
Picking one up for the United States was Shalane Flanagan in the women's 10,000 meters. She won the bronze, finishing behind Elvan Abeylegesse of Turkey and Tirunesh Dibaba of Ethiopia, who set an Olympic record at 29 minutes, 54.66 seconds.
Flanagan, who quizzically flashed three fingers when she crossed to see if it was for real, set an American record at 30:22.22. It was the first American medal in the 10K since Lynn Jennings in 1992.
"Oh my God, am I three?" she asked. "Am I third?"
Yes, and that kept her hopes alive for two medals at these Olympics. She's also entered in the 5,000 next week. Her bronze was all the more impressive because she came down with what she thought was food poisoning earlier this week while wrapping up her training at the U.S. camp in Dalian.
"For 48 hours, it wasn't pretty," Flanagan said.
Medals will be awarded in the 100 on Saturday night. Before that, though, the semifinals offer the first big showdown - Powell vs. Gay in the second heat. Bolt's biggest challenge in the other semi figures to be from Walter Dix of the U.S. and Derrick Atkins of the Bahamas.
Gay was the biggest question mark of the Big Three coming into this, his first Olympics. He hadn't raced in six weeks, when he went tumbling to the track and had to be taken off in a stretcher at the Olympic trials. He was diagnosed with a strained hamstring that he insisted was fine earlier this week.
He did nothing to disprove that in two races Friday, starting cleanly and conserving energy at the end, the way the medal contenders are supposed to.
Also still in play is the three-man American success story in the men's 1,500. Bernard Lagat, Leo Manzano and U.S. team flagbearer Lopez Lomong all made it out of their first races.
Lagat, a double gold medal contender hoping to add to the silver and bronze he won for Kenya in the last two Olympics, showed his trademark kick, moving from 11th to fourth in the final lap of his race.
Lomong, a "Lost Boy" refugee from Sudan, got the fifth and final qualifying spot in his race.
Manzano, at 5-foot-5 and 125 pounds among the smallest in his race, got into a nasty bump-and-push match with Deresse Mekonnen of Ethiopia and finished sixth. That was out of the automatic qualifying - but his time of 3 minutes, 36.67 seconds earned him a wild-card spot in Sunday's semis.
In the 100, Bolt had the fastest time of the second round at 9.92 seconds - the fastest ever run in China - and he made it look easy.
"I just ran the first 50 meters, then I looked around to make sure I was safe and I shut it off," he said.
Even before he slows down, he looks as if he's loping down the track, unfurling his 6-5 frame out of the starting blocks, then taking off - a unique sight in an event supposedly not made for tall men.
"He's a phenomenal athlete," said American Darvis Patton, who also advanced.
But nobody was ceding the race to Bolt, Powell or Gay.
"I know I'm going to win for sure," said Churandy Martina of Netherlands Antilles after winning the first heat with his first official time under 10 seconds - at 9.99, just one of three men to break 10 seconds Friday. "That's why I'm here. If not, I would've stayed home and watched it on TV."
To move on, Martina needs to finish among the top four in the second heat with Gay and Powell.