Tough-talking James Magnussen marked his Olympic debut by leading Australia into the swimming 4x100m freestyle relay final Sunday.

World champion Magnussen dived in at the last change to reel in veteran America’s Jason Lezak to lift Australia into Sunday night’s relay final as top qualifiers.

It was Magnussen’s first swim at the Games and the ‘Missile’ delivered on his brash confidence, clocking a sizzling 47.35 seconds to surge past Lezak (48.04).

Defending Olympic champions America were second quickest ahead of Russia and France.

“I felt nice and relaxed in the first 50 and I just let the crowd carry me home at the end,” Magnussen said.

The Americans, who have won eight of the 10 Olympic gold medals awarded in the event, are expected to bring in big guns Nathan Adrian, Cullen Jones and Michael Phelps for Sunday night’s final.

Sun Yang led the way into the men’s 200m freestyle semi-finals just one day after he gave China its first men’s swimming title.

Australian Emily Seebohm set the pace in the women’s 100m backstroke preliminaries, winning her heat in 58.23sec – an Olympic record and the third-fastest time in history.

US teenager Missy Franklin, swimming in seven events, was second-quickest.