The 100-meter freestyle world champion is at his first Olympics and still pretty new to the game at 21, but he's already made a significant impact.
While Ian Thorpe didn't qualify for the Olympics, Magnussen swam the fastest 100 freestyle ever in a regular textile suit at the Australian trials this year in 47.10 seconds.
Magnussen is pretty straight talking, too, and already in sight of Cesar Cielo's world record of 46.91.
"I think the times I set at trials would point to it (a world record) definitely being a possibility," Magnussen said Monday. "But to be completely honest with you I've come here to win gold, not break world records. At this stage, I think a world record would just be a bonus."
Australia's world champion 100 freestyle relay team also was "absolutely" the team to beat at the Olympics, he said.
It didn't come over as arrogant or trash talking. Just telling it like it is.
"I don't see how you wouldn't be the team to beat coming off a world championship win," Magnussen said.
While Michael Phelps vs. Ryan Lochte is the contest everyone wants to watch at the London Games, Magnussen spearheads the Australian team against its American rivals and will lead the title chase in the 100 free and 100 freestyle relay — two of the marquee swimming events.
Swimming is one of the first sports, with medals decided as soon as Saturday — the second day of the games. Phelps arrived in town Monday.
"And the wait is over... Finally here in (hashtag)London," the 14-time Olympic champion tweeted.
While Phelps will be competing in the Olympics for the last time, this is just the start for Magnussen — Australia's new hope in the pool.
"I feel like if I can overcome the pressures from back home that I know are there. I'm sure I can better my results from last year at the world championships and get the job done," Magnussen said of his battle with 50 and 100 freestyle world-record holder Cielo.
"I know that Cesar holds both world records and I do respect him for that, but I think I'm in a good position to win this one."
The 100 relay has a big history to live up to in London after Jason Lezak's come-frome-behind surge for the United States on the last leg in Beijing four years ago.
That gave Phelps one of his record eight gold medals and led to pumped-up American celebrations on the edge of the pool — one of the lasting images of that games.
"I loved that race. One of my favourite Olympic moments," Magnussen said. "That anchor leg by Jason Lezak is a swim I could only ever dream to emulate. It was such an exciting moment in Olympic sport and such a monumental moment in swimming and is something that I'll remember forever."
Remembering that he'll probably anchor favoured Australia against the Olympic title holder in the relay in London, he added: "We are aware of the Americans' ability to come from behind and forge an upset like that."
Also on Australia's swim team in London are Beijing gold medallists Leisel Jones and Stephanie Rice.
Jones will become the first Australian swimmer to compete in four Olympics, while Rice's rocky buildup to the games — where she's been hampered by both injury and scandal — leaves her uncertain of her chances.
The 200 and 400 individual medley and 200 freestyle relay gold medal winner in Beijing has come through serious shoulder injuries and surgery to make London.
And at least two social media controversies, including a Twitter rant following an Australia rugby game in 2010 that cost her endorsements and led to her being criticized at home.
"It wouldn't be high-pressure preparation without something going not to plan but I feel like I'm really capable of handling things like that at the moment," Rice said of a recent neck problem that's added to the worries. "I'm going to put everything on the line. It hasn't been the perfect prep but we will see what happens."
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