TOKYO — Margaret Mac Neil shrugged off the bull's-eye she felt on her to win Canada's first gold medal of Tokyo's Olympic Games.

The reigning world champion in the women's 100-metre butterfly blitzed the back half of that race Monday at the Tokyo Aquatic Centre.

Seventh at the 50-metre turn, Mac Neil mowed through the pack to win in 55.59 seconds, which is the third-fastest time in the history of the event.

"It was more than I was hoping for at this point," said the 21-year-old from London, Ont. "I was really just trying to enjoy the experience and just have fun, which I think I did today.

"So I'm really proud of that and just trying to not be so nervous and just try to loosen up, which is when I really swim at my best."

The Canadian out-touched silver medallist Zhang Yufei of China by five-hundredths of a second. Australia's Emma McKeon took bronze.

Canada has earned three medals so far. The women's 4-by-100 freestyle relay team of Penny Oleksiak, Kayla Sanchez, Margaret Mac Neil and Rebecca Smith took silver. Jennifer Abel and Melissa Citrini-Beaulieu won silver in the women's three-metre synchro springboard diving competition.