London - American Nathan Adrian edged James Magnussen by a fingertip to win the Olympic 100m freestyle swimming gold Wednesday, just one of the thrillers on a night that saw two world records fall.
Adrian clocked 47.52sec, beating the Australian sprint powerhouse by one one-hundredth of a second.
"I have big hands, I guess," Adrian quipped of the margin of victory over Magnussen, who was fifth at the turn - two spots behind Adrian - but poured it on in the final 50m to make a race of it.
"The second 50 was nerve-wracking," Adrian admitted of the chase to overtake pace-setting world record-holder Cesar Cielo. "I just swam my own race."
Magnussen took silver in 47.53 and Canada's Brent Hayden - second behind Magnussen at last year's world championships - earned bronze in 47.80.
Hungarian Daniel Gyurta got the evening off to a rollicking start with a world record victory in the men's 200m breaststroke.
Rebecca Soni added another world record in the semi-finals of the women's 200m breaststroke, advancing in emphatic style in her defence of the title she won in Beijing.
"Now I am over-shadowed by Reb setting a world record," Adrian jokingly complained.
First, however, it was Gyurta's turn. The two-time world and European champion had seized the lead from defending Olympic gold medallist Kosuke Kitajima by the final turn and stormed home with Britain's Michael Jamieson pushing him all the way.
The duel sent the crowd into a frenzy, but it was Gyurta's gold in 2:07.28.
Jamieson took silver in 2:07.43 and Japan's Ryo Tateishi sneaked past the fading Kitajima to claim bronze in 2:08.29 - a full second adrift.
"It was a really hard race," Gyurta said. "In the last 20m I saw Jamieson, he was so fast in the last part. It was hard for me, but I managed to do it."
Japan's Kitajima, who came into the Games with the fastest 200m time in the world this year, saw his Olympic breaststroke reign ended in a fourth place finish. He had already finished fifth in the 100m breaststroke won in a world record by South African Cameron van der Burgh.
US superstar Michael Phelps meanwhile finished second in a head-to-head semi-final clash with team-mate Ryan Lochte in the 200m individual medley.
Phelps and Lochte were pumped up after watching Adrian's victory.
"It was awesome," Phelps said. "I hope they got us on tape in the ready room when he hit. We were cheering, cheering and cheering and then as soon as he won, Ryan and I went nuts.
Lochte had a busy night, the 200m medley semis coming after he won his 200m backstroke semi to secure his spot in the final with the second-quickest time of the night.
Phelps returned to the pool a day after a 200m butterfly silver and relay gold gave him a record 19 career Olympic medals.
He was clearly enjoying himself and the success of his team-mates on a night that ended with his training partner Allison Schmitt anchoring America to a women's 4x200m freestyle relay victory in an Olympic record of 7:42.92.
Australia finished second in 7:44.41 and France claimed bronze in 7:47.49.
"We are picking up steam and hopefully we can finish well," Phelps said.
Jiao Liuyang kept the gold flowing for rising pool power China as well with a victory in the women's 200m butterfly, four years after settling for silver in Beijing behind team-mate Liu Zige.
Now the world champion, Jiao used a strong second 100m, running down Spain's Mireia Belmonte Garcia to win in an Olympic record of 2:04.06.
Belmonte Garcia settled for silver in 2:05.25 with Japan's Natsumi Hoshi third in 2:05.48.