Johnson started her fight with the incredible stability that gave her the title at last year's world championships, making full advantage of her specialty vault.
She caught the attention of the judges and spectators with a strong opening performance, gaining 15.875 points for an early lead.
But she suddenly dropped to third, behind Yang and Liukin, after the second rotation as the two both giving the best on uneven bars.
Liukin was awarded an awesome 16.650 points, with her dazzling routine on uneven bars and a difficulty of 7.7, while Yang was even better and acquired 16.725, the highest score of the day, equalling Liukin on difficulty but better on execution.
A small sway on balance beam further jeopardized Johnson's title hope, causing a chorus of sighs from the stands. Although Johnson showed the self-possession beyond her age, reconcentrating on her own game and finishing with no more mistakes, a gap of 0.600 points was hard for her to close in the final exercise of floor.
Performing before Johnson, Liukin held her nerves and an almost perfect presentation sent the audience into eruption.
The 15.525 points put Liukin firm on top of the podium and Johnson also leapfrogged Yang after acquiring another 15.525 for her solid performance.
"I was not disappointed at all. I'm happy to finish on the podium and very proud to be here," said Johnson.
"I'm really proud of Nastia. She works very hard and deserves it," she added.
China's Jiang Yuyuan crashed her medal hope after missing her landing on her opening vaulting and finished sixth.
Italy's Vanessa Ferrari, all-around world champion in 2006, was still struggling with her injury. She tumbled before her hands touched the mat after her opening manoeuver on floor and was only 11th after the four rotations.
(Xinhua News Agency August 15, 2008)