Nathan Adrian Edges Out Magnussen for Gold

Nathan Adrian surprised both James Magnussen — the world record-holder in the 100-meter freestyle — by beating him by one-hundredth of a second to win gold Wednesday night.

It was the second time the Chinese American Cal grad has beaten Magnussen at the London games. Adrian, 23, had also finished the opening leg of Saturday’s 400-meter freestyle relay ahead of Magnussen.

When Adrian ripped off his goggles and saw that he had won, he pounded the water then covered his eyes while hanging on the lane rope. Magnussen too seemed to be in a state of disbelief if not shock at having lost his signature event by the smallest margin possible.

‘‘It’s not who swims the fastest time this year,’’ said Adrian. ‘‘It’s who can get their hands on the wall first here tonight.’’

Adrian was referring to the often-observed fact that Olympic medals are often won by staying relaxed and focused in the heat of the big competitions and not by setting records in dry runs.

Adrian’s time of 47.52 seconds is nearly a half second faster than the 48.00 seconds that had been his previous best time in competition but slower than the intimidating 47.10 mark set by Magnussen in March.

Adrian’s is the first US gold in the Olympic’s marquee swimming event since Matt Biondi’s at the 1988 Seoul Olympics.

The bronze medal went to Canada’s Brent Hayden with a time of 47.80 — faster than Adrian’s best time.

‘‘‘We were screaming and everything,” said Ryan Lochte of the gold by one of the US swim team’s best-liked personalities. “That was one of the greatest finishes. We’re so happy for him.’’

Nathan Adrian was born on December 7, 1988 in Bremerton, Washington, the third of three children of a Chinese mother born in Hong Kong and a caucasian father who worked as a nuclear engineer. Adrian’s older sister swam at Arizona State and older brother Justin swam at the University of Washington. Their influence induced Adrian to take up swimming at the age of five. He swam for Bremerton High School before enrolling at UC Berkeley in the fall of 2006. He became one of Cal’s most successful swimmers, winning individual NCAA championships in the 50-yard freestyle in 2009 and 2011 and the 100-yard freestyle in 2009, 2010, and 2011. He also led Cal to the NCAA Swimming National Championship in 2011.

Adrian’s underground popularity on the blogosphere exploded after the 2012 Indianapolis Grand Prix when his suit ripped down the back seam just as he was diving off the block. He won the race anyway — and thousands of new fans who admired not only what the tear revealed about his physique but also about his focus and determination. Those assets are expected to serve him well in London when pressure can produce surprises and upsets.

Adrian has cultivated a large Twitter following with frequent amusing updates about his personal and competitive life. His fans know a great deal about his enthusiasm for yoga and for cooking. Among family and friends his nickname is Bok Choy, a type of Chinese cabbage. At 6-6 and 220 pounds Adrian is the biggest swimmer on the US team.