James "The Missile" Magnussen qualified first for the 100-meter freestyle final but Australian teammate James "The Rocket" Roberts missed out at the Olympics on Tuesday.

Magnussen won the opening heat in 47.63 seconds and Nathan Adrian of the United States qualified second by taking the other heat in 47.97.

Hanser Garcia of Cuba qualified third in 48.04.

Defending 50-meter champion Cesar Cielo of Brazil was fifth and 400-meter winner Yannick Agnel of France made it in seventh.

Roberts had clocked the year's second-fastest time of 47.63 at the Australian trials in March but could only muster a 48.57 this time, putting him in a tie for 12th.

The top eight made it to Wednesday's final of swimming's signature event.